An example showing how to add custom HTTP2 headers (or [metadata](https://grpc.io/grpc/python/glossary.html) in gRPC glossary)

HTTP2 supports initial headers and trailing headers, which gRPC utilizes both of them ([learn more](https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md)).

More complete documentation lives at [grpc.io](https://grpc.io/docs/tutorials/basic/python.html).
For API reference please see [API](https://grpc.io/grpc/python/grpc.html).
