code: def test_level_cache_none(self):
      # This should be equivalent to not set the level cache at all and just work.
      env = self._create_environment(level_cache=None)
      env.reset(episode=1, seed=123)
      env.step(self._dummy_action)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import shutil
  import six
  import tempfile
  from absl.testing import absltest
  import numpy
  import deepmind_lab
label_desc: Use image node_id 8 for calling the LevelCacheTest obj's underlying member method code with example usage: obj.test_level_cache_none() without return types