You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: pingservice.go
    path of file: ./repos/go-grpc-middleware/testing/testpb
    
    the code of the file until where you have to start completion: // Copyright (c) The go-grpc-middleware Authors.
// Licensed under the Apache License 2.0.

/*
Package `grpc_testing` provides helper functions for testing validators in this package.
*/

package testpb

imp
    
func (s *TestPingService) PingList(ping *PingListRequest, stream TestService_PingListServer) error {
	if ping.ErrorCodeReturned != 0 {
		return status.Error(codes.Code(ping.ErrorCodeReturned), "foobar")
	}

	// Send user trailers and headers.
	for i := 0; i < ListResponseCount; i++ {
		if err := stream.Send(&PingListResponse{Value: ping.Value, Counter: int32(i)}); err != nil {
			return err
		}
	}
	return nil
}