class_docstr: Implements of grpc pipeline service.
code: def _run_func(self, request):
      values = self.parse_input(
          self._router_map[request.path].input_model, request.content
      )
      func = self._router_map[request.path].func
      signature = inspect.signature(func)
      if len(signature.parameters.keys()) > 1:
          if isinstance(values, dict):
              ret = func(**values)
          else:
              ret = func(*values)
      elif len(signature.parameters.keys()) == 1:
          ret = func(values)
      else:
          ret = func()
      return self.gen_output(
          self._router_map[request.path].output_model, ret
      )
  
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 4 for calling the _PipelineImpl obj's underlying member method code with example usage: obj._run_func(request) and returns: self