code: def create_downstream(socket_type, tempdir):
      addr, _, channel_creds = _gen_addr_creds(socket_type, tempdir)
  
      channel = grpc.aio.secure_channel(
          addr, credentials=channel_creds, interceptors=[]
      )
  
      return test_server_pb2_grpc.GRPCTestServerStub(channel)
  
file_path: ray/python/ray/serve/_private/benchmarks/streaming/streaming_grpc_throughput.py
imports: import asyncio
  import logging
  import time
  from concurrent import futures
  from tempfile import TemporaryDirectory
  import click
  import grpc
  import ray
  from ray.serve._private.benchmarks.streaming._grpc import test_server_pb2, test_server_pb2_grpc
  from ray.serve._private.benchmarks.streaming._grpc.grpc_server import TestGRPCServer
  from ray.serve._private.benchmarks.streaming.common import Caller, IOMode
label_desc: Use image node_id 2 for calling the GrpcCallerActor obj's underlying member method code with example usage: obj.create_downstream(socket_type, tempdir) and returns: test_server_pb2_grpc