code: def test_set_event_loop_called_once(self):
      # See https://github.com/python/cpython/issues/95736
      async def coro():
          pass
  
      policy = asyncio.get_event_loop_policy()
      policy.set_event_loop = mock.Mock()
      runner = asyncio.Runner()
      runner.run(coro())
      runner.run(coro())
  
      self.assertEqual(1, policy.set_event_loop.call_count)
      runner.close()
  
imports: import _thread
  import asyncio
  import contextvars
  import re
  import signal
  import sys
  import threading
  import unittest
  from test.test_asyncio import utils
  from unittest import mock
  from unittest.mock import patch
label_desc: Use image node_id 16 for calling the RunnerTests obj's underlying member method code with example usage: obj.test_set_event_loop_called_once() without return types