Working bidirectional streaming example

examples/server/proto/example/example.proto

@@ -5,6 +5,7 @@ package go.micro.srv.example;
 service Example {
 	rpc Call(Request) returns (Response) {}
 	rpc Stream(StreamingRequest) returns (stream StreamingResponse) {}
+	rpc PingPong(stream Ping) returns (stream Pong) {}
 }
 
 message Message {
@@ -26,3 +27,11 @@ message StreamingRequest {
 message StreamingResponse {
 	int64 count = 1;
 }
+
+message Ping {
+	int64 stroke = 1;
+}
+
+message Pong {
+	int64 stroke = 1;
+}