code: def test_popen_method(self):
      # make sure that fiber works with multiprocessing
      p = fiber.Process(name="test_popen_method")
      popen = p._Popen(p)
      assert isinstance(popen, fiber.popen_fiber_spawn.Popen)
  
      p = mp.Process(name="test_popen_method2")
      popen = p._Popen(p)
      assert popen.method == "fork"
      assert isinstance(popen, mp.popen_fork.Popen)
  
file_path: fiber/tests/test_popen.py
imports: import multiprocessing
  import io
  import re
  import time
  import logging
  import socket
  import fiber
  import fiber.popen_fiber_spawn
  import docker
  import pytest
label_desc: Use image node_id 5 for calling the TestPopen obj's underlying member method code with example usage: obj.test_popen_method() without return types