code: def plot_grayscale_observation(observation):
      plt.imshow(observation, cmap="gray")
      plt.show()
  
file_path: coach/rl_coach/debug_utils.py
imports: import math
  import matplotlib.pyplot
  import numpy
  from rl_coach.filters.observation.observation_stacking_filter import LazyStack
label_desc: Use image node_id 3 for calling a global function with example usage: plot_grayscale_observation(observation) without return types