code: def test_reset(stack_filter, env_response):
      # stack observation on empty stack
      result = stack_filter.filter(env_response)[0]
      unfiltered_observation = env_response.next_state["observation"]
      filtered_observation = result.next_state["observation"]
  
      assert np.all(
          np.array(filtered_observation)[:, :, :, -1]
          == unfiltered_observation
      )
  
      # reset and make sure the outputs are correct
      stack_filter.reset()
      unfiltered_observation = np.random.rand(20, 30, 1)
      new_env_response = EnvResponse(
          next_state={"observation": unfiltered_observation},
          reward=0,
          game_over=False,
      )
      result = stack_filter.filter(new_env_response)[0]
      filtered_observation = result.next_state["observation"]
      assert np.all(
          np.array(filtered_observation)[:, :, :, 0]
          == unfiltered_observation
      )
      assert np.all(
          np.array(filtered_observation)[:, :, :, -1]
          == unfiltered_observation
      )
  
file_path: coach/rl_coach/tests/filters/observation/test_observation_stacking_filter.py
imports: import os
  import sys
  import pytest
  import numpy
  from rl_coach.filters.observation.observation_stacking_filter import ObservationStackingFilter
  from rl_coach.spaces import ObservationSpace
  from rl_coach.core_types import EnvResponse
  from rl_coach.filters.filter import InputFilter
label_desc: Use image node_id 5 for calling a global function with example usage: test_reset(stack_filter, env_response) without return types