code: def _recv_filter_none(self):
      ret = self._recv()
      assert (
          ret is not None
      ), "[{}] Map function cannot return None when strict mode is used.".format(
          type(self).__name__
      )
      return ret
  
imports: import copy
  import ctypes
  import multiprocessing
  import numpy
  import threading
  import zmq
  from six.moves import queue
  from ..utils.concurrency import StoppableThread, enable_death_signal
  from ..utils.serialize import dumps_once, loads_once
  from .base import DataFlow, DataFlowReentrantGuard, ProxyDataFlow
  from .common import RepeatedData, BatchData
  from .parallel import _bind_guard, _get_pipe_name, _MultiProcessZMQDataFlow, _repeat_iter, _zmq_catch_error
label_desc: Use image node_id 5 for calling the _ParallelMapData obj's underlying member method code with example usage: obj._recv_filter_none() and returns: ret