class_docstr: Implements of grpc pipeline service.
code: def gen_output(self, output_model, ret: T.Any):
      output_model = output_model or TEXT()
      return service_pb2.Response(
          content=output_model.to_proto(ret), code=0, msg="Succ"
      )
  
imports: import typing
  import inspect
  import traceback
  from concurrent import futures
  from towhee.utils.thirdparty.grpc_utils import grpc
  from .None import service_pb2
  from .None import service_pb2_grpc
  from towhee.serve.io import JSON, TEXT, BYTES, NDARRAY
  from towhee.serve.api_service import RouterConfig
  from towhee.utils.log import engine_log
label_desc: Use image node_id 3 for calling the _PipelineImpl obj's underlying member method code with example usage: obj.gen_output(output_model, ret) and returns: service_pb2