code: def rgb_to_y_filter():
      rgb_to_y_filter = InputFilter()
      rgb_to_y_filter.add_observation_filter(
          "observation", "rgb_to_y", ObservationRGBToYFilter()
      )
      return rgb_to_y_filter
  
file_path: coach/rl_coach/tests/filters/observation/test_observation_rgb_to_y_filter.py
imports: import os
  import sys
  import pytest
  import numpy
  from rl_coach.filters.observation.observation_rgb_to_y_filter import ObservationRGBToYFilter
  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: rgb_to_y_filter() and returns: rgb_to_y_filter