diff --git a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/jetbrains.mps.lang.typesystem2.sampleplugin.msd b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/jetbrains.mps.lang.typesystem2.sampleplugin.msd
index 210ee3ba..5c094824 100644
--- a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/jetbrains.mps.lang.typesystem2.sampleplugin.msd
+++ b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/jetbrains.mps.lang.typesystem2.sampleplugin.msd
@@ -8,10 +8,10 @@
   <sourcePath />
   <dependencies>
     <dependency reexport="false">498d89d2-c2e9-11e2-ad49-6cf049e62fe5(MPS.IDEA)</dependency>
-    <dependency reexport="false">a5478664-6b44-4c62-a9f7-434f8aa57eee(jetbrains.mps.logic.runtime)</dependency>
+    <dependency reexport="true">a5478664-6b44-4c62-a9f7-434f8aa57eee(jetbrains.mps.logic.runtime)</dependency>
     <dependency reexport="false">742f6602-5a2f-4313-aa6e-ae1cd4ffdc61(MPS.Platform)</dependency>
     <dependency reexport="false">c7366fe8-43b9-446d-82b3-5cfc76e71f17(jetbrains.mps.typechecking.rules)</dependency>
-    <dependency reexport="false">b984ee52-f34d-4b6d-8812-866c1d3eae31(jetbrains.mps.jchr.runtime)</dependency>
+    <dependency reexport="true">b984ee52-f34d-4b6d-8812-866c1d3eae31(jetbrains.mps.jchr.runtime)</dependency>
     <dependency reexport="false">0d017abe-6cd7-4206-86d5-bfa557885b07(jetbrains.mps.typechecking.handling)</dependency>
     <dependency reexport="false">df9d410f-2ebb-43f7-893a-483a4f085250(jetbrains.mps.smodel.resources)</dependency>
     <dependency reexport="false">26e8f4ce-2a35-4f44-8065-e5ba154b18e9(jetbrains.mps.lang.typesystem2.runtime)</dependency>
diff --git a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
index 70d06b33..f579043c 100644
--- a/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
+++ b/languages/jetbrains.mps.lang.typesystem2/sandbox/jetbrains.mps.lang.typesystem2.sampleplugin/models/jetbrains/mps/lang/typesystem2/sampleplugin/plugin.mps
@@ -288,6 +288,7 @@
       <concept id="1079359253375" name="jetbrains.mps.baseLanguage.structure.ParenthesizedExpression" flags="nn" index="1eOMI4">
         <child id="1079359253376" name="expression" index="1eOMHV" />
       </concept>
+      <concept id="1081506762703" name="jetbrains.mps.baseLanguage.structure.GreaterThanExpression" flags="nn" index="3eOSWO" />
       <concept id="1081506773034" name="jetbrains.mps.baseLanguage.structure.LessThanExpression" flags="nn" index="3eOVzh" />
       <concept id="1081516740877" name="jetbrains.mps.baseLanguage.structure.NotExpression" flags="nn" index="3fqX7Q">
         <child id="1081516765348" name="expression" index="3fr31v" />
@@ -2084,6 +2085,9 @@
                         <node concept="37vLTw" id="61vfVfp2MjS" role="37wK5m">
                           <ref role="3cqZAo" node="61vfVfp2MjL" resolve="tracer" />
                         </node>
+                        <node concept="37vLTw" id="24Vro6cQOGx" role="37wK5m">
+                          <ref role="3cqZAo" node="61vfVfp2MjL" resolve="tracer" />
+                        </node>
                       </node>
                       <node concept="37vLTw" id="41ox5Vnrj9W" role="37vLTJ">
                         <ref role="3cqZAo" node="41ox5VnrfzM" resolve="types" />
@@ -3020,6 +3024,9 @@
                   <node concept="37vLTw" id="4i4XGQZnwa3" role="37wK5m">
                     <ref role="3cqZAo" node="4i4XGQZnvKs" resolve="tracer" />
                   </node>
+                  <node concept="37vLTw" id="24Vro6cQL47" role="37wK5m">
+                    <ref role="3cqZAo" node="24Vro6cQKgF" resolve="cstracer" />
+                  </node>
                   <node concept="37vLTw" id="41ox5Vnmwcf" role="37wK5m">
                     <ref role="3cqZAo" node="41ox5VnkhLF" resolve="sample" />
                   </node>
@@ -3076,6 +3083,12 @@
           <ref role="3uigEE" to="iawt:~Tracer" resolve="Tracer" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cQKgF" role="3clF46">
+        <property role="TrG5h" value="cstracer" />
+        <node concept="3uibUv" id="24Vro6cQKGn" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
     </node>
     <node concept="2tJIrI" id="3gJBs5syXew" role="jymVt" />
     <node concept="2YIFZL" id="3gJBs5syUqI" role="jymVt">
@@ -3864,28 +3877,36 @@
               <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
             </node>
             <node concept="2OqwBi" id="4xBopTzsdVB" role="33vP2m">
-              <node concept="2YIFZM" id="4xBopTzsdVC" role="2Oq$k0">
-                <ref role="37wK5l" to="bspi:6Kcfpq7BWKD" resolve="with" />
-                <ref role="1Pybhc" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
-                <node concept="10M0yZ" id="4xBopTzsdVD" role="37wK5m">
-                  <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
-                  <ref role="3cqZAo" to="oy3s:2GO7tyJY8Rr" resolve="INSTANCE" />
+              <node concept="2OqwBi" id="24Vro6cQH8W" role="2Oq$k0">
+                <node concept="2YIFZM" id="4xBopTzsdVC" role="2Oq$k0">
+                  <ref role="37wK5l" to="bspi:6Kcfpq7BWKD" resolve="with" />
+                  <ref role="1Pybhc" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
+                  <node concept="10M0yZ" id="4xBopTzsdVD" role="37wK5m">
+                    <ref role="1PxDUh" to="oy3s:2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" to="oy3s:2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="10M0yZ" id="4xBopTzsdVE" role="37wK5m">
+                    <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
+                    <ref role="3cqZAo" to="oy3s:3HJTsBn4kQs" resolve="INSTANCE" />
+                  </node>
+                  <node concept="10M0yZ" id="4xBopTzsdVF" role="37wK5m">
+                    <ref role="3cqZAo" to="oy3s:6infEALAhFy" resolve="INSTANCE" />
+                    <ref role="1PxDUh" to="oy3s:6infEALAfer" resolve="AssertBuiltinConstraint" />
+                  </node>
+                  <node concept="10M0yZ" id="5i7izgNi7KH" role="37wK5m">
+                    <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
+                    <ref role="3cqZAo" to="xq5w:5$WbtTOYJJi" resolve="BOUND" />
+                  </node>
+                  <node concept="10M0yZ" id="5i7izgNincb" role="37wK5m">
+                    <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
+                    <ref role="3cqZAo" to="xq5w:5$WbtTOYVUg" resolve="FREE" />
+                  </node>
                 </node>
-                <node concept="10M0yZ" id="4xBopTzsdVE" role="37wK5m">
-                  <ref role="1PxDUh" to="oy3s:3HJTsBn4kk_" resolve="EqualsBuiltinConstraint" />
-                  <ref role="3cqZAo" to="oy3s:3HJTsBn4kQs" resolve="INSTANCE" />
-                </node>
-                <node concept="10M0yZ" id="4xBopTzsdVF" role="37wK5m">
-                  <ref role="3cqZAo" to="oy3s:6infEALAhFy" resolve="INSTANCE" />
-                  <ref role="1PxDUh" to="oy3s:6infEALAfer" resolve="AssertBuiltinConstraint" />
-                </node>
-                <node concept="10M0yZ" id="5i7izgNi7KH" role="37wK5m">
-                  <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
-                  <ref role="3cqZAo" to="xq5w:5$WbtTOYJJi" resolve="BOUND" />
-                </node>
-                <node concept="10M0yZ" id="5i7izgNincb" role="37wK5m">
-                  <ref role="1PxDUh" to="xq5w:5$WbtTOYoMb" resolve="LogicalBuiltinConstraint" />
-                  <ref role="3cqZAo" to="xq5w:5$WbtTOYVUg" resolve="FREE" />
+                <node concept="liA8E" id="24Vro6cQHqz" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQjzH" resolve="withTracer" />
+                  <node concept="37vLTw" id="24Vro6cQHSh" role="37wK5m">
+                    <ref role="3cqZAo" node="24Vro6cQG1d" resolve="cstracer" />
+                  </node>
                 </node>
               </node>
               <node concept="liA8E" id="4xBopTzsdVG" role="2OqNvi">
@@ -4081,6 +4102,12 @@
           <ref role="3uigEE" to="iawt:~Tracer" resolve="Tracer" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cQG1d" role="3clF46">
+        <property role="TrG5h" value="cstracer" />
+        <node concept="3uibUv" id="24Vro6cQGEp" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="37vLTG" id="41ox5VnecVQ" role="3clF46">
         <property role="TrG5h" value="atomToCheck" />
         <node concept="3uibUv" id="41ox5Vned96" role="1tU5fm">
@@ -5178,6 +5205,9 @@
     <node concept="3uibUv" id="4i4XGQZlmNA" role="EKbjA">
       <ref role="3uigEE" to="iawt:~Tracer" resolve="Tracer" />
     </node>
+    <node concept="3uibUv" id="24Vro6cQPQR" role="EKbjA">
+      <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+    </node>
     <node concept="3clFb_" id="4i4XGQZlmRQ" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="activated" />
@@ -5504,6 +5534,124 @@
         </node>
       </node>
     </node>
+    <node concept="2tJIrI" id="24Vro6cQTbM" role="jymVt" />
+    <node concept="3clFb_" id="24Vro6cQSyK" role="jymVt">
+      <property role="1EzhhJ" value="false" />
+      <property role="TrG5h" value="askSuccess" />
+      <node concept="37vLTG" id="24Vro6cQSyL" role="3clF46">
+        <property role="TrG5h" value="autoConstraint" />
+        <node concept="3uibUv" id="24Vro6cQSyM" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:6Kcfpq7Bj7q" resolve="AutoConstraint" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="24Vro6cQSyN" role="3clF46">
+        <property role="TrG5h" value="args" />
+        <node concept="8X2XB" id="24Vro6cQVZK" role="1tU5fm">
+          <node concept="3uibUv" id="24Vro6cQSyP" role="8Xvag">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="24Vro6cQSyQ" role="3clF45" />
+      <node concept="3Tm1VV" id="24Vro6cQSyR" role="1B3o_S" />
+      <node concept="3clFbS" id="24Vro6cQSyT" role="3clF47">
+        <node concept="3clFbF" id="24Vro6cQYOc" role="3cqZAp">
+          <node concept="1rXfSq" id="24Vro6cQYOd" role="3clFbG">
+            <ref role="37wK5l" node="4i4XGQZmbIk" resolve="display" />
+            <node concept="Rm8GO" id="24Vro6cR2fG" role="37wK5m">
+              <ref role="Rm8GQ" node="24Vro6cQUo9" resolve="ASK_SUCCESS" />
+              <ref role="1Px2BO" node="61vfVfp5tJN" resolve="MessageViewTracer.Event" />
+            </node>
+            <node concept="3cpWs3" id="24Vro6cR5wl" role="37wK5m">
+              <node concept="2YIFZM" id="24Vro6cR63s" role="3uHU7w">
+                <ref role="37wK5l" to="33ny:~Arrays.asList(java.lang.Object...):java.util.List" resolve="asList" />
+                <ref role="1Pybhc" to="33ny:~Arrays" resolve="Arrays" />
+                <node concept="37vLTw" id="24Vro6cR6qD" role="37wK5m">
+                  <ref role="3cqZAo" node="24Vro6cQSyN" resolve="args" />
+                </node>
+              </node>
+              <node concept="3cpWs3" id="24Vro6cQYOj" role="3uHU7B">
+                <node concept="3cpWs3" id="24Vro6cQYOk" role="3uHU7B">
+                  <node concept="Xl_RD" id="24Vro6cQYOl" role="3uHU7B">
+                    <property role="Xl_RC" value="[ OK ] /success/ " />
+                  </node>
+                  <node concept="2OqwBi" id="24Vro6cR42_" role="3uHU7w">
+                    <node concept="37vLTw" id="24Vro6cR3Jo" role="2Oq$k0">
+                      <ref role="3cqZAo" node="24Vro6cQSyL" resolve="autoConstraint" />
+                    </node>
+                    <node concept="liA8E" id="24Vro6cR4hF" role="2OqNvi">
+                      <ref role="37wK5l" to="bspi:6Kcfpq7BgtC" resolve="name" />
+                    </node>
+                  </node>
+                </node>
+                <node concept="Xl_RD" id="24Vro6cQYOn" role="3uHU7w">
+                  <property role="Xl_RC" value=" " />
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
+    <node concept="2tJIrI" id="24Vro6cQTLX" role="jymVt" />
+    <node concept="3clFb_" id="24Vro6cQSyU" role="jymVt">
+      <property role="1EzhhJ" value="false" />
+      <property role="TrG5h" value="askFailure" />
+      <node concept="37vLTG" id="24Vro6cQSyV" role="3clF46">
+        <property role="TrG5h" value="autoConstraint" />
+        <node concept="3uibUv" id="24Vro6cQSyW" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:6Kcfpq7Bj7q" resolve="AutoConstraint" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="24Vro6cQSyX" role="3clF46">
+        <property role="TrG5h" value="args" />
+        <node concept="8X2XB" id="24Vro6cQWpv" role="1tU5fm">
+          <node concept="3uibUv" id="24Vro6cQSyZ" role="8Xvag">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="24Vro6cQSz0" role="3clF45" />
+      <node concept="3Tm1VV" id="24Vro6cQSz1" role="1B3o_S" />
+      <node concept="3clFbS" id="24Vro6cQSz3" role="3clF47">
+        <node concept="3clFbF" id="24Vro6cR6WV" role="3cqZAp">
+          <node concept="1rXfSq" id="24Vro6cR6WW" role="3clFbG">
+            <ref role="37wK5l" node="4i4XGQZmbIk" resolve="display" />
+            <node concept="Rm8GO" id="24Vro6cR6WX" role="37wK5m">
+              <ref role="Rm8GQ" node="24Vro6cQUo9" resolve="ASK_SUCCESS" />
+              <ref role="1Px2BO" node="61vfVfp5tJN" resolve="MessageViewTracer.Event" />
+            </node>
+            <node concept="3cpWs3" id="24Vro6cR6WY" role="37wK5m">
+              <node concept="2YIFZM" id="24Vro6cR6WZ" role="3uHU7w">
+                <ref role="1Pybhc" to="33ny:~Arrays" resolve="Arrays" />
+                <ref role="37wK5l" to="33ny:~Arrays.asList(java.lang.Object...):java.util.List" resolve="asList" />
+                <node concept="37vLTw" id="24Vro6cR6X0" role="37wK5m">
+                  <ref role="3cqZAo" node="24Vro6cQSyX" resolve="args" />
+                </node>
+              </node>
+              <node concept="3cpWs3" id="24Vro6cR6X1" role="3uHU7B">
+                <node concept="3cpWs3" id="24Vro6cR6X2" role="3uHU7B">
+                  <node concept="Xl_RD" id="24Vro6cR6X3" role="3uHU7B">
+                    <property role="Xl_RC" value="[FAIL] /failure/ " />
+                  </node>
+                  <node concept="2OqwBi" id="24Vro6cR6X4" role="3uHU7w">
+                    <node concept="37vLTw" id="24Vro6cR6X5" role="2Oq$k0">
+                      <ref role="3cqZAo" node="24Vro6cQSyV" resolve="autoConstraint" />
+                    </node>
+                    <node concept="liA8E" id="24Vro6cR6X6" role="2OqNvi">
+                      <ref role="37wK5l" to="bspi:6Kcfpq7BgtC" resolve="name" />
+                    </node>
+                  </node>
+                </node>
+                <node concept="Xl_RD" id="24Vro6cR6X7" role="3uHU7w">
+                  <property role="Xl_RC" value=" " />
+                </node>
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
     <node concept="2tJIrI" id="4i4XGQZmb7o" role="jymVt" />
     <node concept="3clFb_" id="4i4XGQZmbIk" role="jymVt">
       <property role="TrG5h" value="display" />
@@ -5574,35 +5722,62 @@
           <node concept="3cpWsn" id="4i4XGQZmtTd" role="3cpWs9">
             <property role="TrG5h" value="str" />
             <node concept="17QB3L" id="4i4XGQZmtT9" role="1tU5fm" />
-            <node concept="3cpWs3" id="4i4XGQZmE67" role="33vP2m">
-              <node concept="Xl_RD" id="4i4XGQZmE6u" role="3uHU7w">
-                <property role="Xl_RC" value=")" />
+            <node concept="3cpWs3" id="61vfVfp2U_L" role="33vP2m">
+              <node concept="3cpWs3" id="61vfVfp2UK2" role="3uHU7B">
+                <node concept="37vLTw" id="61vfVfp2UMr" role="3uHU7B">
+                  <ref role="3cqZAo" node="61vfVfp2SU5" resolve="lastRuleTriggered" />
+                </node>
+                <node concept="Xl_RD" id="61vfVfp2UBI" role="3uHU7w">
+                  <property role="Xl_RC" value=" " />
+                </node>
               </node>
-              <node concept="3cpWs3" id="4i4XGQZmDUf" role="3uHU7B">
-                <node concept="3cpWs3" id="4i4XGQZmDDA" role="3uHU7B">
-                  <node concept="3cpWs3" id="61vfVfp2U_L" role="3uHU7B">
-                    <node concept="3cpWs3" id="61vfVfp2UK2" role="3uHU7B">
-                      <node concept="37vLTw" id="61vfVfp2UMr" role="3uHU7B">
-                        <ref role="3cqZAo" node="61vfVfp2SU5" resolve="lastRuleTriggered" />
+              <node concept="37vLTw" id="4i4XGQZmDzB" role="3uHU7w">
+                <ref role="3cqZAo" node="4i4XGQZmczu" resolve="message" />
+              </node>
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbJ" id="24Vro6cSXNy" role="3cqZAp">
+          <node concept="3clFbS" id="24Vro6cSXN$" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cT0ss" role="3cqZAp">
+              <node concept="37vLTI" id="24Vro6cT0y0" role="3clFbG">
+                <node concept="3cpWs3" id="24Vro6cT2an" role="37vLTx">
+                  <node concept="Xl_RD" id="24Vro6cT2n5" role="3uHU7w">
+                    <property role="Xl_RC" value=")" />
+                  </node>
+                  <node concept="3cpWs3" id="24Vro6cT1Cx" role="3uHU7B">
+                    <node concept="3cpWs3" id="24Vro6cT16E" role="3uHU7B">
+                      <node concept="37vLTw" id="24Vro6cT0IV" role="3uHU7B">
+                        <ref role="3cqZAo" node="4i4XGQZmtTd" resolve="str" />
                       </node>
-                      <node concept="Xl_RD" id="61vfVfp2UBI" role="3uHU7w">
-                        <property role="Xl_RC" value=" " />
+                      <node concept="Xl_RD" id="24Vro6cT1lZ" role="3uHU7w">
+                        <property role="Xl_RC" value=" (" />
                       </node>
                     </node>
-                    <node concept="37vLTw" id="4i4XGQZmDzB" role="3uHU7w">
-                      <ref role="3cqZAo" node="4i4XGQZmczu" resolve="message" />
+                    <node concept="37vLTw" id="24Vro6cT1Po" role="3uHU7w">
+                      <ref role="3cqZAo" node="4i4XGQZmDsE" resolve="dbg" />
                     </node>
                   </node>
-                  <node concept="Xl_RD" id="4i4XGQZmDDX" role="3uHU7w">
-                    <property role="Xl_RC" value="(" />
-                  </node>
                 </node>
-                <node concept="37vLTw" id="4i4XGQZmDXv" role="3uHU7w">
-                  <ref role="3cqZAo" node="4i4XGQZmDsE" resolve="dbg" />
+                <node concept="37vLTw" id="24Vro6cT0sq" role="37vLTJ">
+                  <ref role="3cqZAo" node="4i4XGQZmtTd" resolve="str" />
                 </node>
               </node>
             </node>
           </node>
+          <node concept="3eOSWO" id="24Vro6cSZBo" role="3clFbw">
+            <node concept="3cmrfG" id="24Vro6cSZO6" role="3uHU7w">
+              <property role="3cmrfH" value="0" />
+            </node>
+            <node concept="2OqwBi" id="24Vro6cSYBn" role="3uHU7B">
+              <node concept="37vLTw" id="24Vro6cSYfr" role="2Oq$k0">
+                <ref role="3cqZAo" node="4i4XGQZmDsE" resolve="dbg" />
+              </node>
+              <node concept="liA8E" id="24Vro6cSZiO" role="2OqNvi">
+                <ref role="37wK5l" to="wyt6:~String.length():int" resolve="length" />
+              </node>
+            </node>
+          </node>
         </node>
         <node concept="3clFbF" id="4i4XGQZnKvA" role="3cqZAp">
           <node concept="2OqwBi" id="4i4XGQZnK$E" role="3clFbG">
@@ -5685,6 +5860,14 @@
         <property role="TrG5h" value="FIRED" />
         <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
       </node>
+      <node concept="QsSxf" id="24Vro6cQUo9" role="Qtgdg">
+        <property role="TrG5h" value="ASK_SUCCESS" />
+        <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+      </node>
+      <node concept="QsSxf" id="24Vro6cQUIt" role="Qtgdg">
+        <property role="TrG5h" value="ASK_FAILURE" />
+        <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+      </node>
       <node concept="3Tm1VV" id="61vfVfp5tJO" role="1B3o_S" />
     </node>
     <node concept="2tJIrI" id="61vfVfp5tdr" role="jymVt" />
diff --git a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/unification.mps b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/unification.mps
index 9cead4b4..bff169ec 100644
--- a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/unification.mps
+++ b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/unification.mps
@@ -85,6 +85,9 @@
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
+      <concept id="1182160077978" name="jetbrains.mps.baseLanguage.structure.AnonymousClassCreator" flags="nn" index="YeOm9">
+        <child id="1182160096073" name="cls" index="YeSDq" />
+      </concept>
       <concept id="1081236700937" name="jetbrains.mps.baseLanguage.structure.StaticMethodCall" flags="nn" index="2YIFZM">
         <reference id="1144433194310" name="classConcept" index="1Pybhc" />
       </concept>
@@ -247,6 +250,9 @@
       </concept>
       <concept id="1178893518978" name="jetbrains.mps.baseLanguage.structure.ThisConstructorInvocation" flags="nn" index="1VxSAg" />
       <concept id="1080120340718" name="jetbrains.mps.baseLanguage.structure.AndExpression" flags="nn" index="1Wc70l" />
+      <concept id="1170345865475" name="jetbrains.mps.baseLanguage.structure.AnonymousClass" flags="ig" index="1Y3b0j">
+        <reference id="1170346070688" name="classifier" index="1Y3XeK" />
+      </concept>
     </language>
     <language id="fd392034-7849-419d-9071-12563d152375" name="jetbrains.mps.baseLanguage.closures">
       <concept id="1199569711397" name="jetbrains.mps.baseLanguage.closures.structure.ClosureLiteral" flags="nn" index="1bVj0M">
@@ -580,6 +586,7 @@
             <ref role="37wK5l" to="eifs:~ConstraintSystem.get():runtime.ConstraintSystem" resolve="get" />
             <ref role="1Pybhc" to="eifs:~ConstraintSystem" resolve="ConstraintSystem" />
           </node>
+          <node concept="10Nm6u" id="24Vro6cS4RB" role="37wK5m" />
         </node>
       </node>
     </node>
@@ -597,6 +604,7 @@
           <node concept="37vLTw" id="3HJTsBn5PN0" role="37wK5m">
             <ref role="3cqZAo" node="4U_yxogDGlk" resolve="constraintSystem" />
           </node>
+          <node concept="10Nm6u" id="24Vro6cS4Dm" role="37wK5m" />
         </node>
       </node>
       <node concept="37vLTG" id="4U_yxogDGlk" role="3clF46">
@@ -614,6 +622,12 @@
           <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cRCEu" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cRCWH" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3cqZAl" id="3HJTsBn5KhE" role="3clF45" />
       <node concept="3Tm1VV" id="3HJTsBn5KhF" role="1B3o_S" />
       <node concept="3clFbS" id="3HJTsBn5KhG" role="3clF47">
@@ -626,13 +640,16 @@
             <ref role="1Pybhc" to="eifs:~ConstraintSystem" resolve="ConstraintSystem" />
             <ref role="37wK5l" to="eifs:~ConstraintSystem.get():runtime.ConstraintSystem" resolve="get" />
           </node>
+          <node concept="37vLTw" id="24Vro6cS4ev" role="37wK5m">
+            <ref role="3cqZAo" node="24Vro6cRCEu" resolve="tracer" />
+          </node>
         </node>
       </node>
     </node>
     <node concept="2tJIrI" id="5p8T3QHGLEm" role="jymVt" />
     <node concept="3clFbW" id="5p8T3QHGKJ7" role="jymVt">
       <node concept="3cqZAl" id="5p8T3QHGKJ8" role="3clF45" />
-      <node concept="3Tm1VV" id="5p8T3QHGKJ9" role="1B3o_S" />
+      <node concept="3Tm6S6" id="24Vro6cS3ib" role="1B3o_S" />
       <node concept="3clFbS" id="5p8T3QHGKJa" role="3clF47">
         <node concept="3clFbF" id="5p8T3QHGKJb" role="3cqZAp">
           <node concept="37vLTI" id="5p8T3QHGKJc" role="3clFbG">
@@ -660,6 +677,31 @@
             </node>
           </node>
         </node>
+        <node concept="3clFbF" id="24Vro6cS6Oz" role="3cqZAp">
+          <node concept="37vLTI" id="24Vro6cS6O$" role="3clFbG">
+            <node concept="2OqwBi" id="24Vro6cS6O_" role="37vLTJ">
+              <node concept="Xjq3P" id="24Vro6cS6OA" role="2Oq$k0" />
+              <node concept="2OwXpG" id="24Vro6cS6OB" role="2OqNvi">
+                <ref role="2Oxat5" node="24Vro6cRIgn" resolve="tracer" />
+              </node>
+            </node>
+            <node concept="3K4zz7" id="24Vro6cS8Ax" role="37vLTx">
+              <node concept="37vLTw" id="24Vro6cS8BY" role="3K4E3e">
+                <ref role="3cqZAo" node="24Vro6cS3w6" resolve="tracer" />
+              </node>
+              <node concept="3y3z36" id="24Vro6cS8vj" role="3K4Cdx">
+                <node concept="10Nm6u" id="24Vro6cS8yR" role="3uHU7w" />
+                <node concept="37vLTw" id="24Vro6cS6Pb" role="3uHU7B">
+                  <ref role="3cqZAo" node="24Vro6cS3w6" resolve="tracer" />
+                </node>
+              </node>
+              <node concept="10M0yZ" id="24Vro6cS8Di" role="3K4GZi">
+                <ref role="1PxDUh" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+                <ref role="3cqZAo" to="bspi:24Vro6cS5rK" resolve="NULL" />
+              </node>
+            </node>
+          </node>
+        </node>
       </node>
       <node concept="37vLTG" id="4xBopTzo15x" role="3clF46">
         <property role="TrG5h" value="computingSession" />
@@ -673,9 +715,14 @@
           <ref role="3uigEE" to="eifs:~ConstraintSystem" resolve="ConstraintSystem" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cS3w6" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cS3NX" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
     </node>
     <node concept="2tJIrI" id="4U_yxogDCRM" role="jymVt" />
-    <node concept="2tJIrI" id="4xBopTzmuqb" role="jymVt" />
     <node concept="3clFb_" id="4xBopTzmx3e" role="jymVt">
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="ask" />
@@ -2528,6 +2575,26 @@
         </node>
         <node concept="3clFbJ" id="6xYPVrp_rZu" role="3cqZAp">
           <node concept="3clFbS" id="6xYPVrp_rZv" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cRuza" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cRvuy" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cRJzK" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cRJN_" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                  <node concept="10M0yZ" id="24Vro6cROA3" role="37wK5m">
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cRJSf" role="37wK5m">
+                    <ref role="3cqZAo" node="6GYQG_SpvAT" resolve="leftVal" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cRK8v" role="37wK5m">
+                    <ref role="3cqZAo" node="6GYQG_SpvAV" resolve="rightVal" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="6xYPVrp_rZw" role="3cqZAp">
               <node concept="3clFbT" id="6xYPVrp_rZx" role="3cqZAk">
                 <property role="3clFbU" value="false" />
@@ -2550,6 +2617,26 @@
           <node concept="3clFbS" id="6xYPVrp_rZC" role="2LFqv$">
             <node concept="3clFbJ" id="6xYPVrp_rZM" role="3cqZAp">
               <node concept="3clFbS" id="6xYPVrp_rZN" role="3clFbx">
+                <node concept="3clFbF" id="24Vro6cSbG2" role="3cqZAp">
+                  <node concept="2OqwBi" id="24Vro6cSbG3" role="3clFbG">
+                    <node concept="37vLTw" id="24Vro6cSbG4" role="2Oq$k0">
+                      <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                    </node>
+                    <node concept="liA8E" id="24Vro6cSbG5" role="2OqNvi">
+                      <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                      <node concept="10M0yZ" id="24Vro6cSbG6" role="37wK5m">
+                        <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                        <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSbG7" role="37wK5m">
+                        <ref role="3cqZAo" node="6GYQG_SpvAT" resolve="leftVal" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSbG8" role="37wK5m">
+                        <ref role="3cqZAo" node="6GYQG_SpvAV" resolve="rightVal" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
                 <node concept="3cpWs6" id="6xYPVrp_rZO" role="3cqZAp">
                   <node concept="3clFbT" id="6xYPVrp_rZP" role="3cqZAk">
                     <property role="3clFbU" value="false" />
@@ -2606,7 +2693,27 @@
             </node>
           </node>
         </node>
-        <node concept="3clFbH" id="6xYPVrp_s08" role="3cqZAp" />
+        <node concept="3clFbH" id="24Vro6cSeKn" role="3cqZAp" />
+        <node concept="3clFbF" id="24Vro6cScGL" role="3cqZAp">
+          <node concept="2OqwBi" id="24Vro6cScGM" role="3clFbG">
+            <node concept="37vLTw" id="24Vro6cScGN" role="2Oq$k0">
+              <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+            </node>
+            <node concept="liA8E" id="24Vro6cScGO" role="2OqNvi">
+              <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+              <node concept="10M0yZ" id="24Vro6cScGP" role="37wK5m">
+                <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cScGQ" role="37wK5m">
+                <ref role="3cqZAo" node="6GYQG_SpvAT" resolve="leftVal" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cScGR" role="37wK5m">
+                <ref role="3cqZAo" node="6GYQG_SpvAV" resolve="rightVal" />
+              </node>
+            </node>
+          </node>
+        </node>
         <node concept="3cpWs6" id="6xYPVrp_s09" role="3cqZAp">
           <node concept="3clFbT" id="6xYPVrp_s0a" role="3cqZAk">
             <property role="3clFbU" value="true" />
@@ -2709,6 +2816,26 @@
         </node>
         <node concept="3clFbJ" id="4U_yxogDnOp" role="3cqZAp">
           <node concept="3clFbS" id="4U_yxogDnOq" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cSitU" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cSitV" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cSitW" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cSitX" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+                  <node concept="10M0yZ" id="24Vro6cSitY" role="37wK5m">
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSkqp" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC1Ek" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSiu0" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC1Ei" resolve="rightVal" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="4U_yxogDnOr" role="3cqZAp">
               <node concept="3clFbT" id="5oZZzbriPgw" role="3cqZAk">
                 <property role="3clFbU" value="true" />
@@ -2752,6 +2879,26 @@
         </node>
         <node concept="3clFbJ" id="6xYPVrp_lGU" role="3cqZAp">
           <node concept="3clFbS" id="6xYPVrp_lGV" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cSlvx" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cSlvy" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cSlvz" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cSlv$" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                  <node concept="10M0yZ" id="24Vro6cSlv_" role="37wK5m">
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSnBA" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC1Ek" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSlvB" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC1Ei" resolve="rightVal" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="6xYPVrp_lGW" role="3cqZAp">
               <node concept="3clFbT" id="6xYPVrp_lGX" role="3cqZAk">
                 <property role="3clFbU" value="false" />
@@ -2793,6 +2940,26 @@
             <node concept="3clFbH" id="6xYPVrp_lHj" role="3cqZAp" />
             <node concept="3clFbJ" id="6xYPVrp_lHk" role="3cqZAp">
               <node concept="3clFbS" id="6xYPVrp_lHl" role="3clFbx">
+                <node concept="3clFbF" id="24Vro6cSnRh" role="3cqZAp">
+                  <node concept="2OqwBi" id="24Vro6cSnRi" role="3clFbG">
+                    <node concept="37vLTw" id="24Vro6cSnRj" role="2Oq$k0">
+                      <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                    </node>
+                    <node concept="liA8E" id="24Vro6cSnRk" role="2OqNvi">
+                      <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                      <node concept="10M0yZ" id="24Vro6cSnRl" role="37wK5m">
+                        <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                        <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSoWc" role="37wK5m">
+                        <ref role="3cqZAo" node="4U_yxogC1Ek" resolve="left" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSnRn" role="37wK5m">
+                        <ref role="3cqZAo" node="4U_yxogC1Ei" resolve="rightVal" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
                 <node concept="3cpWs6" id="6xYPVrp_lHm" role="3cqZAp">
                   <node concept="3clFbT" id="6xYPVrp_lHn" role="3cqZAk">
                     <property role="3clFbU" value="false" />
@@ -2850,6 +3017,26 @@
           </node>
         </node>
         <node concept="3clFbH" id="6xYPVrp_lHE" role="3cqZAp" />
+        <node concept="3clFbF" id="24Vro6cS$6C" role="3cqZAp">
+          <node concept="2OqwBi" id="24Vro6cS$6D" role="3clFbG">
+            <node concept="37vLTw" id="24Vro6cS$6E" role="2Oq$k0">
+              <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+            </node>
+            <node concept="liA8E" id="24Vro6cS$6F" role="2OqNvi">
+              <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+              <node concept="10M0yZ" id="24Vro6cS$6G" role="37wK5m">
+                <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cS$6H" role="37wK5m">
+                <ref role="3cqZAo" node="4U_yxogC1Ek" resolve="left" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cS$6I" role="37wK5m">
+                <ref role="3cqZAo" node="4U_yxogC1Ei" resolve="rightVal" />
+              </node>
+            </node>
+          </node>
+        </node>
         <node concept="3cpWs6" id="6xYPVrp_lHF" role="3cqZAp">
           <node concept="3clFbT" id="6xYPVrp_lHG" role="3cqZAk">
             <property role="3clFbU" value="true" />
@@ -2891,6 +3078,26 @@
       <node concept="3clFbS" id="4U_yxogC2zF" role="3clF47">
         <node concept="3clFbJ" id="4U_yxogC7xg" role="3cqZAp">
           <node concept="3clFbS" id="4U_yxogC7xh" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cSpbR" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cSpbS" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cSpbT" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cSpbU" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+                  <node concept="10M0yZ" id="24Vro6cSpbV" role="37wK5m">
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSpbW" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSqj2" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="4U_yxogC7Zq" role="3cqZAp">
               <node concept="3clFbT" id="4U_yxogC80f" role="3cqZAk">
                 <property role="3clFbU" value="true" />
@@ -2941,6 +3148,26 @@
         </node>
         <node concept="3clFbJ" id="4U_yxogCA7q" role="3cqZAp">
           <node concept="3clFbS" id="4U_yxogCA7t" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cSqz6" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cSqz7" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cSqz8" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cSqz9" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+                  <node concept="10M0yZ" id="24Vro6cSqza" role="37wK5m">
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSqzb" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSrFx" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="4U_yxogCANm" role="3cqZAp">
               <node concept="3clFbT" id="4U_yxogCAQD" role="3cqZAk">
                 <property role="3clFbU" value="true" />
@@ -2958,6 +3185,26 @@
         </node>
         <node concept="3clFbJ" id="5oZZzbrizbG" role="3cqZAp">
           <node concept="3clFbS" id="5oZZzbrizbH" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cSrV$" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cSrV_" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cSrVA" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cSrVB" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+                  <node concept="10M0yZ" id="24Vro6cSrVC" role="37wK5m">
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSrVD" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSt4y" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="5oZZzbrizbI" role="3cqZAp">
               <node concept="3clFbT" id="7d9KVSzW7Za" role="3cqZAk">
                 <property role="3clFbU" value="true" />
@@ -3019,6 +3266,26 @@
         </node>
         <node concept="3clFbJ" id="6xYPVrp$4Ed" role="3cqZAp">
           <node concept="3clFbS" id="6xYPVrp$4Ef" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cStsT" role="3cqZAp">
+              <node concept="2OqwBi" id="24Vro6cStsU" role="3clFbG">
+                <node concept="37vLTw" id="24Vro6cStsV" role="2Oq$k0">
+                  <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                </node>
+                <node concept="liA8E" id="24Vro6cStsW" role="2OqNvi">
+                  <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                  <node concept="10M0yZ" id="24Vro6cStsX" role="37wK5m">
+                    <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                    <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cStsY" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+                  </node>
+                  <node concept="37vLTw" id="24Vro6cSu_C" role="37wK5m">
+                    <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+                  </node>
+                </node>
+              </node>
+            </node>
             <node concept="3cpWs6" id="6xYPVrp$6uI" role="3cqZAp">
               <node concept="3clFbT" id="6xYPVrp$78l" role="3cqZAk">
                 <property role="3clFbU" value="false" />
@@ -3075,6 +3342,26 @@
             <node concept="3clFbH" id="6xYPVrp_7st" role="3cqZAp" />
             <node concept="3clFbJ" id="6xYPVrp_7w8" role="3cqZAp">
               <node concept="3clFbS" id="6xYPVrp_7wa" role="3clFbx">
+                <node concept="3clFbF" id="24Vro6cSuPB" role="3cqZAp">
+                  <node concept="2OqwBi" id="24Vro6cSuPC" role="3clFbG">
+                    <node concept="37vLTw" id="24Vro6cSuPD" role="2Oq$k0">
+                      <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+                    </node>
+                    <node concept="liA8E" id="24Vro6cSuPE" role="2OqNvi">
+                      <ref role="37wK5l" to="bspi:24Vro6cQCzk" resolve="askFailure" />
+                      <node concept="10M0yZ" id="24Vro6cSuPF" role="37wK5m">
+                        <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+                        <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSuPG" role="37wK5m">
+                        <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+                      </node>
+                      <node concept="37vLTw" id="24Vro6cSvYT" role="37wK5m">
+                        <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
                 <node concept="3cpWs6" id="6xYPVrp_8fn" role="3cqZAp">
                   <node concept="3clFbT" id="6xYPVrp_8LE" role="3cqZAk">
                     <property role="3clFbU" value="false" />
@@ -3131,7 +3418,27 @@
             </node>
           </node>
         </node>
-        <node concept="3clFbH" id="6xYPVrp_ajM" role="3cqZAp" />
+        <node concept="3clFbH" id="24Vro6cSyV3" role="3cqZAp" />
+        <node concept="3clFbF" id="24Vro6cSweS" role="3cqZAp">
+          <node concept="2OqwBi" id="24Vro6cSweT" role="3clFbG">
+            <node concept="37vLTw" id="24Vro6cSweU" role="2Oq$k0">
+              <ref role="3cqZAo" node="24Vro6cRIgn" resolve="tracer" />
+            </node>
+            <node concept="liA8E" id="24Vro6cSweV" role="2OqNvi">
+              <ref role="37wK5l" to="bspi:24Vro6cQC7A" resolve="askSuccess" />
+              <node concept="10M0yZ" id="24Vro6cSweW" role="37wK5m">
+                <ref role="3cqZAo" node="2GO7tyJY8Rr" resolve="INSTANCE" />
+                <ref role="1PxDUh" node="2GO7tyJVmP4" resolve="UnificationBuiltinConstraint" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cSweX" role="37wK5m">
+                <ref role="3cqZAo" node="4U_yxogC2zy" resolve="left" />
+              </node>
+              <node concept="37vLTw" id="24Vro6cSxsn" role="37wK5m">
+                <ref role="3cqZAo" node="4U_yxogC2z$" resolve="right" />
+              </node>
+            </node>
+          </node>
+        </node>
         <node concept="3cpWs6" id="3HJTsBn3F6H" role="3cqZAp">
           <node concept="3clFbT" id="6xYPVrp_bB3" role="3cqZAk">
             <property role="3clFbU" value="true" />
@@ -3835,6 +4142,108 @@
         </node>
       </node>
     </node>
+    <node concept="2tJIrI" id="24Vro6cRYFv" role="jymVt" />
+    <node concept="3clFb_" id="24Vro6cROT9" role="jymVt">
+      <property role="TrG5h" value="setTracer" />
+      <node concept="3Tm6S6" id="24Vro6cROTa" role="1B3o_S" />
+      <node concept="3cqZAl" id="24Vro6cROTb" role="3clF45" />
+      <node concept="37vLTG" id="24Vro6cROT4" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cROT5" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
+      <node concept="3clFbS" id="24Vro6cROSX" role="3clF47">
+        <node concept="3clFbF" id="24Vro6cROSY" role="3cqZAp">
+          <node concept="37vLTI" id="24Vro6cROSZ" role="3clFbG">
+            <node concept="2OqwBi" id="24Vro6cROT0" role="37vLTJ">
+              <node concept="Xjq3P" id="24Vro6cROT1" role="2Oq$k0" />
+              <node concept="2OwXpG" id="24Vro6cROT2" role="2OqNvi">
+                <ref role="2Oxat5" node="24Vro6cRIgn" resolve="tracer" />
+              </node>
+            </node>
+            <node concept="37vLTw" id="24Vro6cROT6" role="37vLTx">
+              <ref role="3cqZAo" node="24Vro6cROT4" resolve="tracer" />
+            </node>
+          </node>
+        </node>
+        <node concept="3clFbJ" id="24Vro6cS0vJ" role="3cqZAp">
+          <node concept="3clFbS" id="24Vro6cS0vL" role="3clFbx">
+            <node concept="3clFbF" id="24Vro6cS1sJ" role="3cqZAp">
+              <node concept="37vLTI" id="24Vro6cS2yt" role="3clFbG">
+                <node concept="2ShNRf" id="24Vro6cS2zE" role="37vLTx">
+                  <node concept="YeOm9" id="24Vro6cS2Sz" role="2ShVmc">
+                    <node concept="1Y3b0j" id="24Vro6cS2SA" role="YeSDq">
+                      <property role="2bfB8j" value="true" />
+                      <ref role="1Y3XeK" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+                      <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+                      <node concept="3Tm1VV" id="24Vro6cS2SB" role="1B3o_S" />
+                      <node concept="3clFb_" id="24Vro6cS2SC" role="jymVt">
+                        <property role="1EzhhJ" value="false" />
+                        <property role="TrG5h" value="askSuccess" />
+                        <node concept="37vLTG" id="24Vro6cS2SD" role="3clF46">
+                          <property role="TrG5h" value="autoConstraint" />
+                          <node concept="3uibUv" id="24Vro6cS2SE" role="1tU5fm">
+                            <ref role="3uigEE" to="bspi:6Kcfpq7Bj7q" resolve="AutoConstraint" />
+                          </node>
+                        </node>
+                        <node concept="37vLTG" id="24Vro6cS2SF" role="3clF46">
+                          <property role="TrG5h" value="args" />
+                          <node concept="8X2XB" id="24Vro6cS2SG" role="1tU5fm">
+                            <node concept="3uibUv" id="24Vro6cS2SH" role="8Xvag">
+                              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                            </node>
+                          </node>
+                        </node>
+                        <node concept="3cqZAl" id="24Vro6cS2SI" role="3clF45" />
+                        <node concept="3Tm1VV" id="24Vro6cS2SJ" role="1B3o_S" />
+                        <node concept="3clFbS" id="24Vro6cS2SL" role="3clF47" />
+                      </node>
+                      <node concept="3clFb_" id="24Vro6cS2SN" role="jymVt">
+                        <property role="1EzhhJ" value="false" />
+                        <property role="TrG5h" value="askFailure" />
+                        <node concept="37vLTG" id="24Vro6cS2SO" role="3clF46">
+                          <property role="TrG5h" value="autoConstraint" />
+                          <node concept="3uibUv" id="24Vro6cS2SP" role="1tU5fm">
+                            <ref role="3uigEE" to="bspi:6Kcfpq7Bj7q" resolve="AutoConstraint" />
+                          </node>
+                        </node>
+                        <node concept="37vLTG" id="24Vro6cS2SQ" role="3clF46">
+                          <property role="TrG5h" value="args" />
+                          <node concept="8X2XB" id="24Vro6cS2SR" role="1tU5fm">
+                            <node concept="3uibUv" id="24Vro6cS2SS" role="8Xvag">
+                              <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                            </node>
+                          </node>
+                        </node>
+                        <node concept="3cqZAl" id="24Vro6cS2ST" role="3clF45" />
+                        <node concept="3Tm1VV" id="24Vro6cS2SU" role="1B3o_S" />
+                        <node concept="3clFbS" id="24Vro6cS2SW" role="3clF47" />
+                      </node>
+                    </node>
+                  </node>
+                </node>
+                <node concept="2OqwBi" id="24Vro6cS1$0" role="37vLTJ">
+                  <node concept="Xjq3P" id="24Vro6cS1sI" role="2Oq$k0" />
+                  <node concept="2OwXpG" id="24Vro6cS25d" role="2OqNvi">
+                    <ref role="2Oxat5" node="24Vro6cRIgn" resolve="tracer" />
+                  </node>
+                </node>
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbC" id="24Vro6cS0z3" role="3clFbw">
+            <node concept="10Nm6u" id="24Vro6cS0$1" role="3uHU7w" />
+            <node concept="2OqwBi" id="24Vro6cS0HA" role="3uHU7B">
+              <node concept="Xjq3P" id="24Vro6cS0Ab" role="2Oq$k0" />
+              <node concept="2OwXpG" id="24Vro6cS1eW" role="2OqNvi">
+                <ref role="2Oxat5" node="24Vro6cRIgn" resolve="tracer" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
+    </node>
     <node concept="2tJIrI" id="1bm7a6EU93j" role="jymVt" />
     <node concept="312cEg" id="4xBopTznWRz" role="jymVt">
       <property role="TrG5h" value="computingSession" />
@@ -3850,6 +4259,13 @@
         <ref role="3uigEE" to="eifs:~ConstraintSystem" resolve="ConstraintSystem" />
       </node>
     </node>
+    <node concept="312cEg" id="24Vro6cRIgn" role="jymVt">
+      <property role="TrG5h" value="tracer" />
+      <node concept="3Tm6S6" id="24Vro6cRIgo" role="1B3o_S" />
+      <node concept="3uibUv" id="24Vro6cRIgq" role="1tU5fm">
+        <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+      </node>
+    </node>
   </node>
   <node concept="312cEu" id="4U_yxogAknZ">
     <property role="TrG5h" value="AtomLogical" />
@@ -4928,6 +5344,12 @@
           <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cRB6v" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cRB6w" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3clFbS" id="4xBopTzmp9n" role="3clF47">
         <node concept="3clFbF" id="4xBopTznD$v" role="3cqZAp">
           <node concept="3nyPlj" id="4xBopTznD$u" role="3clFbG">
@@ -4941,6 +5363,9 @@
                 <node concept="37vLTw" id="4xBopTznF6e" role="37wK5m">
                   <ref role="3cqZAo" node="4xBopTzmp9j" resolve="session" />
                 </node>
+                <node concept="37vLTw" id="24Vro6cRBd8" role="37wK5m">
+                  <ref role="3cqZAo" node="24Vro6cRB6v" resolve="tracer" />
+                </node>
               </node>
             </node>
           </node>
@@ -6440,6 +6865,12 @@
           <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cRA82" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cRA83" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3clFbS" id="4xBopTzopK3" role="3clF47">
         <node concept="3clFbF" id="4xBopTzoDmY" role="3cqZAp">
           <node concept="3nyPlj" id="4xBopTzoDmX" role="3clFbG">
@@ -9144,6 +9575,12 @@
           <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cR_QP" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cR_S2" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3clFbS" id="4xBopTzs1yd" role="3clF47">
         <node concept="3clFbF" id="4xBopTzs52D" role="3cqZAp">
           <node concept="3nyPlj" id="4xBopTzs52C" role="3clFbG">
diff --git a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/var.mps b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/var.mps
index d7c3db35..5934b2ec 100644
--- a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/var.mps
+++ b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/builtin/var.mps
@@ -460,6 +460,12 @@
           <ref role="3uigEE" to="bspi:6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cR_QP" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cR_S2" role="1tU5fm">
+          <ref role="3uigEE" to="bspi:24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3clFbS" id="4xBopTzr9JA" role="3clF47">
         <node concept="3clFbF" id="4xBopTzrjSy" role="3cqZAp">
           <node concept="3nyPlj" id="4xBopTzrjSx" role="3clFbG">
diff --git a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/constraint.mps b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/constraint.mps
index 65d7aa8e..6c0c7071 100644
--- a/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/constraint.mps
+++ b/languages/jetbrains.mps.logic/runtime/models/jetbrains/mps/logic/constraint.mps
@@ -6,9 +6,9 @@
     <use id="f2801650-65d5-424e-bb1b-463a8781b786" name="jetbrains.mps.baseLanguage.javadoc" version="2" />
   </languages>
   <imports>
-    <import index="k7g3" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/f:java_stub#6354ebe7-c22a-4a0f-ac54-50b52ab9b065#java.util(JDK/java.util@java_stub)" />
+    <import index="33ny" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.util(JDK/)" />
     <import index="oy3s" ref="r:a6030cee-34eb-4503-b1bf-015fe5cd8c1a(jetbrains.mps.logic.builtin.unification)" />
-    <import index="e2lb" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/f:java_stub#6354ebe7-c22a-4a0f-ac54-50b52ab9b065#java.lang(JDK/java.lang@java_stub)" implicit="true" />
+    <import index="wyt6" ref="6354ebe7-c22a-4a0f-ac54-50b52ab9b065/java:java.lang(JDK/)" implicit="true" />
   </imports>
   <registry>
     <language id="f3061a53-9226-4cc5-a443-f952ceaf5816" name="jetbrains.mps.baseLanguage">
@@ -44,10 +44,14 @@
       <concept id="1145552977093" name="jetbrains.mps.baseLanguage.structure.GenericNewExpression" flags="nn" index="2ShNRf">
         <child id="1145553007750" name="creator" index="2ShVmc" />
       </concept>
+      <concept id="1070462154015" name="jetbrains.mps.baseLanguage.structure.StaticFieldDeclaration" flags="ig" index="Wx3nA" />
       <concept id="1070475354124" name="jetbrains.mps.baseLanguage.structure.ThisExpression" flags="nn" index="Xjq3P" />
       <concept id="1070475926800" name="jetbrains.mps.baseLanguage.structure.StringLiteral" flags="nn" index="Xl_RD">
         <property id="1070475926801" name="value" index="Xl_RC" />
       </concept>
+      <concept id="1182160077978" name="jetbrains.mps.baseLanguage.structure.AnonymousClassCreator" flags="nn" index="YeOm9">
+        <child id="1182160096073" name="cls" index="YeSDq" />
+      </concept>
       <concept id="1081236700938" name="jetbrains.mps.baseLanguage.structure.StaticMethodDeclaration" flags="ig" index="2YIFZL" />
       <concept id="1081236700937" name="jetbrains.mps.baseLanguage.structure.StaticMethodCall" flags="nn" index="2YIFZM">
         <reference id="1144433194310" name="classConcept" index="1Pybhc" />
@@ -72,6 +76,7 @@
         <child id="1095933932569" name="implementedInterface" index="EKbjA" />
       </concept>
       <concept id="1068431474542" name="jetbrains.mps.baseLanguage.structure.VariableDeclaration" flags="ng" index="33uBYm">
+        <property id="1176718929932" name="isFinal" index="3TUv4t" />
         <child id="1068431790190" name="initializer" index="33vP2m" />
       </concept>
       <concept id="1092119917967" name="jetbrains.mps.baseLanguage.structure.MulExpression" flags="nn" index="17qRlL" />
@@ -172,6 +177,9 @@
       <concept id="1146644602865" name="jetbrains.mps.baseLanguage.structure.PublicVisibility" flags="nn" index="3Tm1VV" />
       <concept id="1146644623116" name="jetbrains.mps.baseLanguage.structure.PrivateVisibility" flags="nn" index="3Tm6S6" />
       <concept id="1146644641414" name="jetbrains.mps.baseLanguage.structure.ProtectedVisibility" flags="nn" index="3Tmbuc" />
+      <concept id="1170345865475" name="jetbrains.mps.baseLanguage.structure.AnonymousClass" flags="ig" index="1Y3b0j">
+        <reference id="1170346070688" name="classifier" index="1Y3XeK" />
+      </concept>
     </language>
     <language id="f2801650-65d5-424e-bb1b-463a8781b786" name="jetbrains.mps.baseLanguage.javadoc">
       <concept id="5349172909345501395" name="jetbrains.mps.baseLanguage.javadoc.structure.BaseDocComment" flags="ng" index="P$AiS">
@@ -210,7 +218,7 @@
         <property role="TrG5h" value="arg" />
         <node concept="8X2XB" id="6Kcfpq7AYvU" role="1tU5fm">
           <node concept="3uibUv" id="6Kcfpq7AYox" role="8Xvag">
-            <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
           </node>
         </node>
       </node>
@@ -237,7 +245,7 @@
         <property role="TrG5h" value="arg" />
         <node concept="8X2XB" id="6Kcfpq7AZc0" role="1tU5fm">
           <node concept="3uibUv" id="6Kcfpq7AZ4J" role="8Xvag">
-            <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
           </node>
         </node>
       </node>
@@ -311,9 +319,29 @@
     </node>
     <node concept="2tJIrI" id="6Kcfpq7BY0I" role="jymVt" />
     <node concept="3clFbW" id="6Kcfpq7BJaF" role="jymVt">
+      <node concept="37vLTG" id="24Vro6cQB61" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cQBin" role="1tU5fm">
+          <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
       <node concept="3cqZAl" id="6Kcfpq7BJaH" role="3clF45" />
       <node concept="3Tm6S6" id="6Kcfpq7CfrR" role="1B3o_S" />
-      <node concept="3clFbS" id="6Kcfpq7BJaJ" role="3clF47" />
+      <node concept="3clFbS" id="6Kcfpq7BJaJ" role="3clF47">
+        <node concept="3clFbF" id="24Vro6cQBEg" role="3cqZAp">
+          <node concept="37vLTI" id="24Vro6cQBHr" role="3clFbG">
+            <node concept="37vLTw" id="24Vro6cQBIm" role="37vLTx">
+              <ref role="3cqZAo" node="24Vro6cQB61" resolve="tracer" />
+            </node>
+            <node concept="2OqwBi" id="24Vro6cQBEw" role="37vLTJ">
+              <node concept="Xjq3P" id="24Vro6cQBEf" role="2Oq$k0" />
+              <node concept="2OwXpG" id="24Vro6cQBGy" role="2OqNvi">
+                <ref role="2Oxat5" node="24Vro6cQyK4" resolve="tracer" />
+              </node>
+            </node>
+          </node>
+        </node>
+      </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7Bmmj" role="jymVt" />
     <node concept="312cEu" id="6Kcfpq7BTQb" role="jymVt">
@@ -339,10 +367,10 @@
                 <ref role="3cqZAo" node="6Kcfpq7C1nA" resolve="items" />
               </node>
               <node concept="liA8E" id="6Kcfpq7C2kY" role="2OqNvi">
-                <ref role="37wK5l" to="k7g3:~List.addAll(java.util.Collection):boolean" resolve="addAll" />
+                <ref role="37wK5l" to="33ny:~List.addAll(java.util.Collection):boolean" resolve="addAll" />
                 <node concept="2YIFZM" id="6Kcfpq7C3Zw" role="37wK5m">
-                  <ref role="37wK5l" to="k7g3:~Arrays.asList(java.lang.Object...):java.util.List" resolve="asList" />
-                  <ref role="1Pybhc" to="k7g3:~Arrays" resolve="Arrays" />
+                  <ref role="37wK5l" to="33ny:~Arrays.asList(java.lang.Object...):java.util.List" resolve="asList" />
+                  <ref role="1Pybhc" to="33ny:~Arrays" resolve="Arrays" />
                   <node concept="37vLTw" id="6Kcfpq7C440" role="37wK5m">
                     <ref role="3cqZAo" node="6Kcfpq7BXbe" resolve="item" />
                   </node>
@@ -354,6 +382,38 @@
         <node concept="3Tm6S6" id="6Kcfpq7BWZN" role="1B3o_S" />
       </node>
       <node concept="2tJIrI" id="6Kcfpq7BU6m" role="jymVt" />
+      <node concept="3clFb_" id="24Vro6cQjzH" role="jymVt">
+        <property role="TrG5h" value="withTracer" />
+        <node concept="37vLTG" id="24Vro6cQl7h" role="3clF46">
+          <property role="TrG5h" value="tracer" />
+          <node concept="3uibUv" id="24Vro6cQoAS" role="1tU5fm">
+            <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+          </node>
+        </node>
+        <node concept="3uibUv" id="24Vro6cQk4j" role="3clF45">
+          <ref role="3uigEE" node="6Kcfpq7BTQb" resolve="ComputingSession.Builder" />
+        </node>
+        <node concept="3Tm1VV" id="24Vro6cQjzK" role="1B3o_S" />
+        <node concept="3clFbS" id="24Vro6cQjzL" role="3clF47">
+          <node concept="3clFbF" id="24Vro6cQoBu" role="3cqZAp">
+            <node concept="37vLTI" id="24Vro6cQoBw" role="3clFbG">
+              <node concept="2OqwBi" id="24Vro6cQoB$" role="37vLTJ">
+                <node concept="Xjq3P" id="24Vro6cQoBB" role="2Oq$k0" />
+                <node concept="2OwXpG" id="24Vro6cQoBz" role="2OqNvi">
+                  <ref role="2Oxat5" node="24Vro6cQoBq" resolve="tracer" />
+                </node>
+              </node>
+              <node concept="37vLTw" id="24Vro6cQoBC" role="37vLTx">
+                <ref role="3cqZAo" node="24Vro6cQl7h" resolve="tracer" />
+              </node>
+            </node>
+          </node>
+          <node concept="3clFbF" id="24Vro6cQpEB" role="3cqZAp">
+            <node concept="Xjq3P" id="24Vro6cQpE_" role="3clFbG" />
+          </node>
+        </node>
+      </node>
+      <node concept="2tJIrI" id="24Vro6cQj3q" role="jymVt" />
       <node concept="3clFb_" id="6Kcfpq7Cgrc" role="jymVt">
         <property role="TrG5h" value="newSession" />
         <node concept="3uibUv" id="6Kcfpq7CgVs" role="3clF45">
@@ -369,6 +429,9 @@
               <node concept="2ShNRf" id="6Kcfpq7Ci9q" role="33vP2m">
                 <node concept="1pGfFk" id="6Kcfpq7Ci9r" role="2ShVmc">
                   <ref role="37wK5l" node="6Kcfpq7BJaF" resolve="ComputingSession" />
+                  <node concept="37vLTw" id="24Vro6cQBJH" role="37wK5m">
+                    <ref role="3cqZAo" node="24Vro6cQoBq" resolve="tracer" />
+                  </node>
                 </node>
               </node>
             </node>
@@ -385,6 +448,9 @@
                     <node concept="37vLTw" id="6Kcfpq7CrcZ" role="37wK5m">
                       <ref role="3cqZAo" node="6Kcfpq7Ci9p" resolve="session" />
                     </node>
+                    <node concept="37vLTw" id="24Vro6cRGxU" role="37wK5m">
+                      <ref role="3cqZAo" node="24Vro6cQoBq" resolve="tracer" />
+                    </node>
                   </node>
                 </node>
               </node>
@@ -408,60 +474,35 @@
         <node concept="3Tm1VV" id="6Kcfpq7CgII" role="1B3o_S" />
       </node>
       <node concept="2tJIrI" id="6Kcfpq7Cg9v" role="jymVt" />
-      <node concept="3clFb_" id="6Kcfpq7C0y0" role="jymVt">
-        <property role="TrG5h" value="addItem" />
-        <node concept="37vLTG" id="6Kcfpq7C1a5" role="3clF46">
-          <property role="TrG5h" value="cst" />
-          <node concept="3uibUv" id="6Kcfpq7CoZC" role="1tU5fm">
-            <ref role="3uigEE" node="6Kcfpq7CkpJ" resolve="ComputingItem" />
-          </node>
-        </node>
-        <node concept="3uibUv" id="6Kcfpq7C0FJ" role="3clF45">
-          <ref role="3uigEE" node="6Kcfpq7BTQb" resolve="ComputingSession.Builder" />
-        </node>
-        <node concept="3clFbS" id="6Kcfpq7C0y3" role="3clF47">
-          <node concept="3clFbF" id="6Kcfpq7C4Uh" role="3cqZAp">
-            <node concept="2OqwBi" id="6Kcfpq7C552" role="3clFbG">
-              <node concept="37vLTw" id="6Kcfpq7C4Ug" role="2Oq$k0">
-                <ref role="3cqZAo" node="6Kcfpq7C1nA" resolve="items" />
-              </node>
-              <node concept="liA8E" id="6Kcfpq7C5lt" role="2OqNvi">
-                <ref role="37wK5l" to="k7g3:~List.add(java.lang.Object):boolean" resolve="add" />
-                <node concept="37vLTw" id="6Kcfpq7C5r5" role="37wK5m">
-                  <ref role="3cqZAo" node="6Kcfpq7C1a5" resolve="cst" />
-                </node>
-              </node>
-            </node>
-          </node>
-          <node concept="3cpWs6" id="6Kcfpq7CeB5" role="3cqZAp">
-            <node concept="Xjq3P" id="6Kcfpq7CeE$" role="3cqZAk" />
-          </node>
-        </node>
-        <node concept="3Tm1VV" id="6Kcfpq7C0C5" role="1B3o_S" />
-      </node>
-      <node concept="2tJIrI" id="6Kcfpq7C5T4" role="jymVt" />
       <node concept="312cEg" id="6Kcfpq7C1nA" role="jymVt">
         <property role="TrG5h" value="items" />
         <node concept="3Tm6S6" id="6Kcfpq7C1nB" role="1B3o_S" />
         <node concept="3uibUv" id="6Kcfpq7C1q$" role="1tU5fm">
-          <ref role="3uigEE" to="k7g3:~List" resolve="List" />
+          <ref role="3uigEE" to="33ny:~List" resolve="List" />
           <node concept="3uibUv" id="6Kcfpq7CmUd" role="11_B2D">
             <ref role="3uigEE" node="6Kcfpq7CkpJ" resolve="ComputingItem" />
           </node>
         </node>
         <node concept="2ShNRf" id="6Kcfpq7C1rR" role="33vP2m">
           <node concept="1pGfFk" id="6Kcfpq7C1wG" role="2ShVmc">
-            <ref role="37wK5l" to="k7g3:~ArrayList.&lt;init&gt;()" resolve="ArrayList" />
+            <ref role="37wK5l" to="33ny:~ArrayList.&lt;init&gt;()" resolve="ArrayList" />
             <node concept="3uibUv" id="6Kcfpq7Cn4o" role="1pMfVU">
               <ref role="3uigEE" node="6Kcfpq7CkpJ" resolve="ComputingItem" />
             </node>
           </node>
         </node>
       </node>
-      <node concept="2tJIrI" id="6Kcfpq7Cnoi" role="jymVt" />
       <node concept="3Tm1VV" id="4xBopTzuEuZ" role="1B3o_S" />
+      <node concept="312cEg" id="24Vro6cQoBq" role="jymVt">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3Tm6S6" id="24Vro6cQoBr" role="1B3o_S" />
+        <node concept="3uibUv" id="24Vro6cQoBt" role="1tU5fm">
+          <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7BSVl" role="jymVt" />
+    <node concept="2tJIrI" id="24Vro6cQmg2" role="jymVt" />
     <node concept="3clFb_" id="4xBopTznHV5" role="jymVt">
       <property role="TrG5h" value="ask" />
       <node concept="37vLTG" id="4xBopTznJFk" role="3clF46">
@@ -474,7 +515,7 @@
         <property role="TrG5h" value="arg" />
         <node concept="8X2XB" id="4xBopTznKlF" role="1tU5fm">
           <node concept="3uibUv" id="4xBopTznKj7" role="8Xvag">
-            <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
           </node>
         </node>
       </node>
@@ -500,7 +541,7 @@
             <node concept="YS8fn" id="2GO7tyJTJIH" role="3cqZAp">
               <node concept="2ShNRf" id="2GO7tyJTJJ5" role="YScLw">
                 <node concept="1pGfFk" id="2GO7tyJTJXR" role="2ShVmc">
-                  <ref role="37wK5l" to="e2lb:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
+                  <ref role="37wK5l" to="wyt6:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
                   <node concept="3cpWs3" id="2GO7tyJTLcI" role="37wK5m">
                     <node concept="Xl_RD" id="2GO7tyJTLcT" role="3uHU7w">
                       <property role="Xl_RC" value="'" />
@@ -574,7 +615,7 @@
             <node concept="YS8fn" id="4xBopTznRO3" role="3cqZAp">
               <node concept="2ShNRf" id="4xBopTznRO4" role="YScLw">
                 <node concept="1pGfFk" id="4xBopTznRO5" role="2ShVmc">
-                  <ref role="37wK5l" to="e2lb:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
+                  <ref role="37wK5l" to="wyt6:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
                   <node concept="3cpWs3" id="4xBopTznRO6" role="37wK5m">
                     <node concept="Xl_RD" id="4xBopTznRO7" role="3uHU7w">
                       <property role="Xl_RC" value="'" />
@@ -632,7 +673,7 @@
         <property role="TrG5h" value="arg" />
         <node concept="8X2XB" id="4xBopTznRwA" role="1tU5fm">
           <node concept="3uibUv" id="4xBopTznRsM" role="8Xvag">
-            <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
           </node>
         </node>
       </node>
@@ -643,7 +684,7 @@
       <node concept="37vLTG" id="4xBopTzsx3E" role="3clF46">
         <property role="TrG5h" value="clazz" />
         <node concept="3uibUv" id="4xBopTzsxtj" role="1tU5fm">
-          <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+          <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
           <node concept="3qTvmN" id="4xBopTzuGaJ" role="11_B2D" />
         </node>
       </node>
@@ -662,7 +703,7 @@
                       <ref role="3cqZAo" node="4xBopTzsFsF" resolve="e" />
                     </node>
                     <node concept="liA8E" id="4xBopTzsFsy" role="2OqNvi">
-                      <ref role="37wK5l" to="k7g3:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
+                      <ref role="37wK5l" to="33ny:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
                     </node>
                   </node>
                 </node>
@@ -672,14 +713,14 @@
                   <ref role="3cqZAo" node="4xBopTzsx3E" resolve="clazz" />
                 </node>
                 <node concept="liA8E" id="4xBopTzsFs_" role="2OqNvi">
-                  <ref role="37wK5l" to="e2lb:~Class.isAssignableFrom(java.lang.Class):boolean" resolve="isAssignableFrom" />
+                  <ref role="37wK5l" to="wyt6:~Class.isAssignableFrom(java.lang.Class):boolean" resolve="isAssignableFrom" />
                   <node concept="2OqwBi" id="4xBopTzsFsA" role="37wK5m">
                     <node concept="2OqwBi" id="4xBopTzsFsB" role="2Oq$k0">
                       <node concept="37vLTw" id="4xBopTzsFsC" role="2Oq$k0">
                         <ref role="3cqZAo" node="4xBopTzsFsF" resolve="e" />
                       </node>
                       <node concept="liA8E" id="4xBopTzsFsD" role="2OqNvi">
-                        <ref role="37wK5l" to="k7g3:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
+                        <ref role="37wK5l" to="33ny:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
                       </node>
                     </node>
                     <node concept="liA8E" id="4xBopTzsFsE" role="2OqNvi">
@@ -693,7 +734,7 @@
           <node concept="3cpWsn" id="4xBopTzsFsF" role="1Duv9x">
             <property role="TrG5h" value="e" />
             <node concept="3uibUv" id="4xBopTzsFsG" role="1tU5fm">
-              <ref role="3uigEE" to="k7g3:~Map$Entry" resolve="Map.Entry" />
+              <ref role="3uigEE" to="33ny:~Map$Entry" resolve="Map.Entry" />
               <node concept="3uibUv" id="4xBopTzsFGt" role="11_B2D">
                 <ref role="3uigEE" node="6Kcfpq7BfEn" resolve="Constraint" />
               </node>
@@ -707,7 +748,7 @@
               <ref role="3cqZAo" node="2GO7tyJTzV1" resolve="handlers" />
             </node>
             <node concept="liA8E" id="4xBopTzsFsL" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.entrySet():java.util.Set" resolve="entrySet" />
+              <ref role="37wK5l" to="33ny:~Map.entrySet():java.util.Set" resolve="entrySet" />
             </node>
           </node>
         </node>
@@ -722,7 +763,7 @@
       <node concept="37vLTG" id="4xBopTzsxxt" role="3clF46">
         <property role="TrG5h" value="clazz" />
         <node concept="3uibUv" id="4xBopTzsxxu" role="1tU5fm">
-          <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+          <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
           <node concept="3qTvmN" id="4xBopTzuGiG" role="11_B2D" />
         </node>
       </node>
@@ -741,7 +782,7 @@
                       <ref role="3cqZAo" node="4xBopTzs_7D" resolve="e" />
                     </node>
                     <node concept="liA8E" id="4xBopTzsCqM" role="2OqNvi">
-                      <ref role="37wK5l" to="k7g3:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
+                      <ref role="37wK5l" to="33ny:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
                     </node>
                   </node>
                 </node>
@@ -751,14 +792,14 @@
                   <ref role="3cqZAo" node="4xBopTzsxxt" resolve="clazz" />
                 </node>
                 <node concept="liA8E" id="4xBopTzs_AV" role="2OqNvi">
-                  <ref role="37wK5l" to="e2lb:~Class.isAssignableFrom(java.lang.Class):boolean" resolve="isAssignableFrom" />
+                  <ref role="37wK5l" to="wyt6:~Class.isAssignableFrom(java.lang.Class):boolean" resolve="isAssignableFrom" />
                   <node concept="2OqwBi" id="4xBopTzs_JA" role="37wK5m">
                     <node concept="2OqwBi" id="4xBopTzs_Ed" role="2Oq$k0">
                       <node concept="37vLTw" id="4xBopTzs_CO" role="2Oq$k0">
                         <ref role="3cqZAo" node="4xBopTzs_7D" resolve="e" />
                       </node>
                       <node concept="liA8E" id="4xBopTzs_GQ" role="2OqNvi">
-                        <ref role="37wK5l" to="k7g3:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
+                        <ref role="37wK5l" to="33ny:~Map$Entry.getKey():java.lang.Object" resolve="getKey" />
                       </node>
                     </node>
                     <node concept="liA8E" id="4xBopTzsA_A" role="2OqNvi">
@@ -772,7 +813,7 @@
           <node concept="3cpWsn" id="4xBopTzs_7D" role="1Duv9x">
             <property role="TrG5h" value="e" />
             <node concept="3uibUv" id="4xBopTzs_7H" role="1tU5fm">
-              <ref role="3uigEE" to="k7g3:~Map$Entry" resolve="Map.Entry" />
+              <ref role="3uigEE" to="33ny:~Map$Entry" resolve="Map.Entry" />
               <node concept="3uibUv" id="4xBopTzsAtJ" role="11_B2D">
                 <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
               </node>
@@ -786,7 +827,7 @@
               <ref role="3cqZAo" node="6Kcfpq7B51L" resolve="solvers" />
             </node>
             <node concept="liA8E" id="4xBopTzs_7M" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.entrySet():java.util.Set" resolve="entrySet" />
+              <ref role="37wK5l" to="33ny:~Map.entrySet():java.util.Set" resolve="entrySet" />
             </node>
           </node>
         </node>
@@ -814,7 +855,7 @@
             <node concept="YS8fn" id="6Kcfpq7B83r" role="3cqZAp">
               <node concept="2ShNRf" id="6Kcfpq7B83J" role="YScLw">
                 <node concept="1pGfFk" id="6Kcfpq7B8cz" role="2ShVmc">
-                  <ref role="37wK5l" to="e2lb:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
+                  <ref role="37wK5l" to="wyt6:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
                   <node concept="3cpWs3" id="6Kcfpq7B8lK" role="37wK5m">
                     <node concept="37vLTw" id="6Kcfpq7B8n0" role="3uHU7w">
                       <ref role="3cqZAo" node="6Kcfpq7B0U_" resolve="constraint" />
@@ -833,7 +874,7 @@
                 <ref role="3cqZAo" node="2GO7tyJTzV1" resolve="handlers" />
               </node>
               <node concept="liA8E" id="6Kcfpq7B7VP" role="2OqNvi">
-                <ref role="37wK5l" to="k7g3:~Map.containsKey(java.lang.Object):boolean" resolve="containsKey" />
+                <ref role="37wK5l" to="33ny:~Map.containsKey(java.lang.Object):boolean" resolve="containsKey" />
                 <node concept="37vLTw" id="6Kcfpq7B7Z$" role="37wK5m">
                   <ref role="3cqZAo" node="6Kcfpq7B0U_" resolve="constraint" />
                 </node>
@@ -847,7 +888,7 @@
               <ref role="3cqZAo" node="2GO7tyJTzV1" resolve="handlers" />
             </node>
             <node concept="liA8E" id="6Kcfpq7Ba26" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.get(java.lang.Object):java.lang.Object" resolve="get" />
+              <ref role="37wK5l" to="33ny:~Map.get(java.lang.Object):java.lang.Object" resolve="get" />
               <node concept="37vLTw" id="6Kcfpq7Ba5I" role="37wK5m">
                 <ref role="3cqZAo" node="6Kcfpq7B0U_" resolve="constraint" />
               </node>
@@ -875,7 +916,7 @@
             <node concept="YS8fn" id="6Kcfpq7BaRt" role="3cqZAp">
               <node concept="2ShNRf" id="6Kcfpq7BaRu" role="YScLw">
                 <node concept="1pGfFk" id="6Kcfpq7BaRv" role="2ShVmc">
-                  <ref role="37wK5l" to="e2lb:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
+                  <ref role="37wK5l" to="wyt6:~IllegalStateException.&lt;init&gt;(java.lang.String)" resolve="IllegalStateException" />
                   <node concept="3cpWs3" id="6Kcfpq7BaRw" role="37wK5m">
                     <node concept="37vLTw" id="6Kcfpq7BaRx" role="3uHU7w">
                       <ref role="3cqZAo" node="6Kcfpq7B10P" resolve="constraint" />
@@ -894,7 +935,7 @@
                 <ref role="3cqZAo" node="6Kcfpq7B51L" resolve="solvers" />
               </node>
               <node concept="liA8E" id="6Kcfpq7BaRA" role="2OqNvi">
-                <ref role="37wK5l" to="k7g3:~Map.containsKey(java.lang.Object):boolean" resolve="containsKey" />
+                <ref role="37wK5l" to="33ny:~Map.containsKey(java.lang.Object):boolean" resolve="containsKey" />
                 <node concept="37vLTw" id="6Kcfpq7BaRB" role="37wK5m">
                   <ref role="3cqZAo" node="6Kcfpq7B10P" resolve="constraint" />
                 </node>
@@ -908,7 +949,7 @@
               <ref role="3cqZAo" node="6Kcfpq7B51L" resolve="solvers" />
             </node>
             <node concept="liA8E" id="6Kcfpq7BaRF" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.get(java.lang.Object):java.lang.Object" resolve="get" />
+              <ref role="37wK5l" to="33ny:~Map.get(java.lang.Object):java.lang.Object" resolve="get" />
               <node concept="37vLTw" id="6Kcfpq7BaRG" role="37wK5m">
                 <ref role="3cqZAo" node="6Kcfpq7B10P" resolve="constraint" />
               </node>
@@ -929,7 +970,7 @@
               <ref role="3cqZAo" node="2GO7tyJTzV1" resolve="handlers" />
             </node>
             <node concept="liA8E" id="6Kcfpq7BcnH" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
+              <ref role="37wK5l" to="33ny:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
               <node concept="37vLTw" id="6Kcfpq7Bcu$" role="37wK5m">
                 <ref role="3cqZAo" node="6Kcfpq7B2G3" resolve="constraint" />
               </node>
@@ -965,7 +1006,7 @@
               <ref role="3cqZAo" node="6Kcfpq7B51L" resolve="solvers" />
             </node>
             <node concept="liA8E" id="6Kcfpq7BcWr" role="2OqNvi">
-              <ref role="37wK5l" to="k7g3:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
+              <ref role="37wK5l" to="33ny:~Map.put(java.lang.Object,java.lang.Object):java.lang.Object" resolve="put" />
               <node concept="37vLTw" id="6Kcfpq7Bd4J" role="37wK5m">
                 <ref role="3cqZAo" node="6Kcfpq7B2LZ" resolve="constraint" />
               </node>
@@ -994,7 +1035,7 @@
       <property role="TrG5h" value="handlers" />
       <node concept="3Tm6S6" id="2GO7tyJTzV2" role="1B3o_S" />
       <node concept="3uibUv" id="2GO7tyJT$59" role="1tU5fm">
-        <ref role="3uigEE" to="k7g3:~Map" resolve="Map" />
+        <ref role="3uigEE" to="33ny:~Map" resolve="Map" />
         <node concept="3uibUv" id="4xBopTzs_Ou" role="11_B2D">
           <ref role="3uigEE" node="6Kcfpq7BfEn" resolve="Constraint" />
         </node>
@@ -1004,7 +1045,7 @@
       </node>
       <node concept="2ShNRf" id="2GO7tyJTFoC" role="33vP2m">
         <node concept="1pGfFk" id="2GO7tyJTFM0" role="2ShVmc">
-          <ref role="37wK5l" to="k7g3:~HashMap.&lt;init&gt;()" resolve="HashMap" />
+          <ref role="37wK5l" to="33ny:~HashMap.&lt;init&gt;()" resolve="HashMap" />
           <node concept="3uibUv" id="4xBopTzs_UT" role="1pMfVU">
             <ref role="3uigEE" node="6Kcfpq7BfEn" resolve="Constraint" />
           </node>
@@ -1019,7 +1060,7 @@
       <property role="TrG5h" value="solvers" />
       <node concept="3Tm6S6" id="6Kcfpq7B51M" role="1B3o_S" />
       <node concept="3uibUv" id="6Kcfpq7B51N" role="1tU5fm">
-        <ref role="3uigEE" to="k7g3:~Map" resolve="Map" />
+        <ref role="3uigEE" to="33ny:~Map" resolve="Map" />
         <node concept="3uibUv" id="4xBopTzsAf6" role="11_B2D">
           <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
         </node>
@@ -1029,7 +1070,7 @@
       </node>
       <node concept="2ShNRf" id="6Kcfpq7B51Q" role="33vP2m">
         <node concept="1pGfFk" id="6Kcfpq7B51R" role="2ShVmc">
-          <ref role="37wK5l" to="k7g3:~HashMap.&lt;init&gt;()" resolve="HashMap" />
+          <ref role="37wK5l" to="33ny:~HashMap.&lt;init&gt;()" resolve="HashMap" />
           <node concept="3uibUv" id="4xBopTzsA13" role="1pMfVU">
             <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
           </node>
@@ -1048,6 +1089,14 @@
         </node>
       </node>
     </node>
+    <node concept="312cEg" id="24Vro6cQyK4" role="jymVt">
+      <property role="TrG5h" value="tracer" />
+      <property role="3TUv4t" value="true" />
+      <node concept="3Tm6S6" id="24Vro6cQyK5" role="1B3o_S" />
+      <node concept="3uibUv" id="24Vro6cQyK7" role="1tU5fm">
+        <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+      </node>
+    </node>
   </node>
   <node concept="312cEu" id="6Kcfpq7B0Wu">
     <property role="TrG5h" value="AbstractConstraint" />
@@ -1198,7 +1247,7 @@
       <property role="1EzhhJ" value="true" />
       <property role="TrG5h" value="solverClass" />
       <node concept="3uibUv" id="4xBopTzt6NP" role="3clF45">
-        <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+        <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
         <node concept="3qUE_q" id="4xBopTzt6NQ" role="11_B2D">
           <node concept="3uibUv" id="4xBopTzt6NR" role="3qUE_r">
             <ref role="3uigEE" node="6Kcfpq7AYBh" resolve="Queryable" />
@@ -1213,7 +1262,7 @@
       <property role="1EzhhJ" value="false" />
       <property role="TrG5h" value="handlerClass" />
       <node concept="3uibUv" id="4xBopTzs1yo" role="3clF45">
-        <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+        <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
         <node concept="3qUE_q" id="4xBopTzs1yp" role="11_B2D">
           <node concept="3uibUv" id="4xBopTzs1yq" role="3qUE_r">
             <ref role="3uigEE" node="6Kcfpq7AXVG" resolve="Instructible" />
@@ -1237,7 +1286,7 @@
       <property role="IEkAT" value="false" />
       <node concept="3Tm1VV" id="6Kcfpq7B8WE" role="1B3o_S" />
       <node concept="3uibUv" id="6Kcfpq7B8WG" role="3clF45">
-        <ref role="3uigEE" to="e2lb:~String" resolve="String" />
+        <ref role="3uigEE" to="wyt6:~String" resolve="String" />
       </node>
       <node concept="3clFbS" id="6Kcfpq7B8WH" role="3clF47">
         <node concept="3clFbF" id="6Kcfpq7B99k" role="3cqZAp">
@@ -1247,7 +1296,7 @@
         </node>
       </node>
       <node concept="2AHcQZ" id="6Kcfpq7B8WI" role="2AJF6D">
-        <ref role="2AI5Lk" to="e2lb:~Override" resolve="Override" />
+        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
       </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7BBoK" role="jymVt" />
@@ -1414,7 +1463,7 @@
               <node concept="2OqwBi" id="6Kcfpq7B2Wo" role="3uHU7B">
                 <node concept="Xjq3P" id="6Kcfpq7B2Wp" role="2Oq$k0" />
                 <node concept="liA8E" id="6Kcfpq7B2Wq" role="2OqNvi">
-                  <ref role="37wK5l" to="e2lb:~Object.getClass():java.lang.Class" resolve="getClass" />
+                  <ref role="37wK5l" to="wyt6:~Object.getClass():java.lang.Class" resolve="getClass" />
                 </node>
               </node>
               <node concept="2OqwBi" id="6Kcfpq7B2Wr" role="3uHU7w">
@@ -1422,7 +1471,7 @@
                   <ref role="3cqZAo" node="6Kcfpq7B2W_" resolve="o" />
                 </node>
                 <node concept="liA8E" id="6Kcfpq7B2Wt" role="2OqNvi">
-                  <ref role="37wK5l" to="e2lb:~Object.getClass():java.lang.Class" resolve="getClass" />
+                  <ref role="37wK5l" to="wyt6:~Object.getClass():java.lang.Class" resolve="getClass" />
                 </node>
               </node>
             </node>
@@ -1457,7 +1506,7 @@
             <node concept="3fqX7Q" id="6Kcfpq7B2WO" role="3K4E3e">
               <node concept="2OqwBi" id="6Kcfpq7B2WP" role="3fr31v">
                 <node concept="liA8E" id="6Kcfpq7B2WQ" role="2OqNvi">
-                  <ref role="37wK5l" to="e2lb:~Object.equals(java.lang.Object):boolean" resolve="equals" />
+                  <ref role="37wK5l" to="wyt6:~Object.equals(java.lang.Object):boolean" resolve="equals" />
                   <node concept="2OqwBi" id="6Kcfpq7B2WR" role="37wK5m">
                     <node concept="37vLTw" id="6Kcfpq7B2WC" role="2Oq$k0">
                       <ref role="3cqZAo" node="6Kcfpq7B2Ww" resolve="that" />
@@ -1470,7 +1519,7 @@
                 <node concept="1eOMI4" id="6Kcfpq7B2WS" role="2Oq$k0">
                   <node concept="10QFUN" id="6Kcfpq7B2WT" role="1eOMHV">
                     <node concept="3uibUv" id="6Kcfpq7B2WU" role="10QFUM">
-                      <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+                      <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
                     </node>
                     <node concept="37vLTw" id="6Kcfpq7B2WG" role="10QFUP">
                       <ref role="3cqZAo" node="6Kcfpq7B1jt" resolve="symbol" />
@@ -1508,11 +1557,11 @@
       <node concept="37vLTG" id="6Kcfpq7B2W_" role="3clF46">
         <property role="TrG5h" value="o" />
         <node concept="3uibUv" id="6Kcfpq7B2WA" role="1tU5fm">
-          <ref role="3uigEE" to="e2lb:~Object" resolve="Object" />
+          <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
         </node>
       </node>
       <node concept="2AHcQZ" id="6Kcfpq7B2WB" role="2AJF6D">
-        <ref role="2AI5Lk" to="e2lb:~Override" resolve="Override" />
+        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
       </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7B3h2" role="jymVt" />
@@ -1557,14 +1606,14 @@
                   </node>
                   <node concept="2OqwBi" id="6Kcfpq7B2Xv" role="3K4E3e">
                     <node concept="2YIFZM" id="6Kcfpq7B2Xw" role="2Oq$k0">
-                      <ref role="1Pybhc" to="e2lb:~String" resolve="String" />
-                      <ref role="37wK5l" to="e2lb:~String.valueOf(java.lang.Object):java.lang.String" resolve="valueOf" />
+                      <ref role="1Pybhc" to="wyt6:~String" resolve="String" />
+                      <ref role="37wK5l" to="wyt6:~String.valueOf(java.lang.Object):java.lang.String" resolve="valueOf" />
                       <node concept="37vLTw" id="6Kcfpq7B2Xl" role="37wK5m">
                         <ref role="3cqZAo" node="6Kcfpq7B1jt" resolve="symbol" />
                       </node>
                     </node>
                     <node concept="liA8E" id="6Kcfpq7B2Xx" role="2OqNvi">
-                      <ref role="37wK5l" to="e2lb:~String.hashCode():int" resolve="hashCode" />
+                      <ref role="37wK5l" to="wyt6:~String.hashCode():int" resolve="hashCode" />
                     </node>
                   </node>
                 </node>
@@ -1579,7 +1628,7 @@
         </node>
       </node>
       <node concept="2AHcQZ" id="6Kcfpq7B2X8" role="2AJF6D">
-        <ref role="2AI5Lk" to="e2lb:~Override" resolve="Override" />
+        <ref role="2AI5Lk" to="wyt6:~Override" resolve="Override" />
       </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7B3IY" role="jymVt" />
@@ -1627,7 +1676,7 @@
       <property role="1EzhhJ" value="true" />
       <property role="TrG5h" value="handlerClass" />
       <node concept="3uibUv" id="4xBopTzlOqK" role="3clF45">
-        <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+        <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
         <node concept="3qUE_q" id="4xBopTzlOqU" role="11_B2D">
           <node concept="3uibUv" id="4xBopTzlOr0" role="3qUE_r">
             <ref role="3uigEE" node="6Kcfpq7AXVG" resolve="Instructible" />
@@ -1689,7 +1738,7 @@
       <property role="1EzhhJ" value="true" />
       <property role="TrG5h" value="solverClass" />
       <node concept="3uibUv" id="4xBopTzlOts" role="3clF45">
-        <ref role="3uigEE" to="e2lb:~Class" resolve="Class" />
+        <ref role="3uigEE" to="wyt6:~Class" resolve="Class" />
         <node concept="3qUE_q" id="4xBopTzlOtB" role="11_B2D">
           <node concept="3uibUv" id="4xBopTzlOtH" role="3qUE_r">
             <ref role="3uigEE" node="6Kcfpq7AYBh" resolve="Queryable" />
@@ -1743,6 +1792,12 @@
           <ref role="3uigEE" node="6Kcfpq7B0b0" resolve="ComputingSession" />
         </node>
       </node>
+      <node concept="37vLTG" id="24Vro6cR_QP" role="3clF46">
+        <property role="TrG5h" value="tracer" />
+        <node concept="3uibUv" id="24Vro6cR_S2" role="1tU5fm">
+          <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+        </node>
+      </node>
     </node>
     <node concept="2tJIrI" id="6Kcfpq7CkXB" role="jymVt" />
     <node concept="3clFb_" id="6Kcfpq7CkV4" role="jymVt">
@@ -1768,5 +1823,115 @@
       </node>
     </node>
   </node>
+  <node concept="3HP615" id="24Vro6cQnrj">
+    <property role="2bfB8j" value="true" />
+    <property role="TrG5h" value="ComputingTracer" />
+    <node concept="2tJIrI" id="24Vro6cQoAz" role="jymVt" />
+    <node concept="3clFb_" id="24Vro6cQC7A" role="jymVt">
+      <property role="1EzhhJ" value="true" />
+      <property role="TrG5h" value="askSuccess" />
+      <node concept="37vLTG" id="24Vro6cQCnj" role="3clF46">
+        <property role="TrG5h" value="autoConstraint" />
+        <node concept="3uibUv" id="24Vro6cQCn$" role="1tU5fm">
+          <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="24Vro6cQCoe" role="3clF46">
+        <property role="TrG5h" value="args" />
+        <node concept="8X2XB" id="24Vro6cQVdR" role="1tU5fm">
+          <node concept="3uibUv" id="24Vro6cQCoD" role="8Xvag">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="24Vro6cQC7C" role="3clF45" />
+      <node concept="3Tm1VV" id="24Vro6cQC7D" role="1B3o_S" />
+      <node concept="3clFbS" id="24Vro6cQC7E" role="3clF47" />
+    </node>
+    <node concept="2tJIrI" id="24Vro6cQCMn" role="jymVt" />
+    <node concept="3clFb_" id="24Vro6cQCzk" role="jymVt">
+      <property role="1EzhhJ" value="true" />
+      <property role="TrG5h" value="askFailure" />
+      <node concept="37vLTG" id="24Vro6cQCzl" role="3clF46">
+        <property role="TrG5h" value="autoConstraint" />
+        <node concept="3uibUv" id="24Vro6cQCzm" role="1tU5fm">
+          <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
+        </node>
+      </node>
+      <node concept="37vLTG" id="24Vro6cQCzn" role="3clF46">
+        <property role="TrG5h" value="args" />
+        <node concept="8X2XB" id="24Vro6cQVv5" role="1tU5fm">
+          <node concept="3uibUv" id="24Vro6cQCzp" role="8Xvag">
+            <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+          </node>
+        </node>
+      </node>
+      <node concept="3cqZAl" id="24Vro6cQCzq" role="3clF45" />
+      <node concept="3Tm1VV" id="24Vro6cQCzr" role="1B3o_S" />
+      <node concept="3clFbS" id="24Vro6cQCzs" role="3clF47" />
+    </node>
+    <node concept="2tJIrI" id="24Vro6cQoAO" role="jymVt" />
+    <node concept="Wx3nA" id="24Vro6cS5rK" role="jymVt">
+      <property role="3TUv4t" value="true" />
+      <property role="TrG5h" value="NULL" />
+      <node concept="3Tm1VV" id="24Vro6cS5rM" role="1B3o_S" />
+      <node concept="2ShNRf" id="24Vro6cS5M$" role="33vP2m">
+        <node concept="YeOm9" id="24Vro6cS5SL" role="2ShVmc">
+          <node concept="1Y3b0j" id="24Vro6cS5SO" role="YeSDq">
+            <property role="2bfB8j" value="true" />
+            <ref role="1Y3XeK" node="24Vro6cQnrj" resolve="ComputingTracer" />
+            <ref role="37wK5l" to="wyt6:~Object.&lt;init&gt;()" resolve="Object" />
+            <node concept="3Tm1VV" id="24Vro6cS5SP" role="1B3o_S" />
+            <node concept="3clFb_" id="24Vro6cS5SQ" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="askSuccess" />
+              <node concept="37vLTG" id="24Vro6cS5SR" role="3clF46">
+                <property role="TrG5h" value="autoConstraint" />
+                <node concept="3uibUv" id="24Vro6cS5SS" role="1tU5fm">
+                  <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="24Vro6cS5ST" role="3clF46">
+                <property role="TrG5h" value="args" />
+                <node concept="8X2XB" id="24Vro6cS5SU" role="1tU5fm">
+                  <node concept="3uibUv" id="24Vro6cS5SV" role="8Xvag">
+                    <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3cqZAl" id="24Vro6cS5SW" role="3clF45" />
+              <node concept="3Tm1VV" id="24Vro6cS5SX" role="1B3o_S" />
+              <node concept="3clFbS" id="24Vro6cS5SZ" role="3clF47" />
+            </node>
+            <node concept="3clFb_" id="24Vro6cS5T1" role="jymVt">
+              <property role="1EzhhJ" value="false" />
+              <property role="TrG5h" value="askFailure" />
+              <node concept="37vLTG" id="24Vro6cS5T2" role="3clF46">
+                <property role="TrG5h" value="autoConstraint" />
+                <node concept="3uibUv" id="24Vro6cS5T3" role="1tU5fm">
+                  <ref role="3uigEE" node="6Kcfpq7Bj7q" resolve="AutoConstraint" />
+                </node>
+              </node>
+              <node concept="37vLTG" id="24Vro6cS5T4" role="3clF46">
+                <property role="TrG5h" value="args" />
+                <node concept="8X2XB" id="24Vro6cS5T5" role="1tU5fm">
+                  <node concept="3uibUv" id="24Vro6cS5T6" role="8Xvag">
+                    <ref role="3uigEE" to="wyt6:~Object" resolve="Object" />
+                  </node>
+                </node>
+              </node>
+              <node concept="3cqZAl" id="24Vro6cS5T7" role="3clF45" />
+              <node concept="3Tm1VV" id="24Vro6cS5T8" role="1B3o_S" />
+              <node concept="3clFbS" id="24Vro6cS5Ta" role="3clF47" />
+            </node>
+          </node>
+        </node>
+      </node>
+      <node concept="3uibUv" id="24Vro6cS5Ii" role="1tU5fm">
+        <ref role="3uigEE" node="24Vro6cQnrj" resolve="ComputingTracer" />
+      </node>
+    </node>
+    <node concept="3Tm1VV" id="24Vro6cQnrk" role="1B3o_S" />
+  </node>
 </model>