code: def env_response():
      observation = np.random.rand(20, 30, 1)
      return EnvResponse(
          next_state={"observation": observation},
          reward=0,
          game_over=False,
      )
  
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 1 for calling a global function with example usage: env_response() and returns: EnvResponse