class_docstr: Mock environment for testing.
code: def reset(self):
      self.ale.screen_value = 10
      self.num_steps = 0
      return self.get_observation()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from gym import core
  import numpy
  import tensorflow
  from tf_agents.environments import atari_preprocessing
label_desc: Use image node_id 2 for calling the MockEnvironment obj's underlying member method code with example usage: obj.reset() and returns: self