code: def check_obs(obs, batch_size, grid_size):
      assert len(obs) == 2, "two players"
      for i in range(batch_size):
          for key, player_obs in obs.items():
              assert player_obs.shape == (
                  batch_size,
                  grid_size,
                  grid_size,
                  4,
              )
              assert (
                  player_obs[i, ..., 0].sum() == 1.0
              ), f"observe 1 player red in grid: {player_obs[i, ..., 0]}"
              assert (
                  player_obs[i, ..., 1].sum() == 1.0
              ), f"observe 1 player blue in grid: {player_obs[i, ..., 1]}"
              assert (
                  player_obs[i, ..., 2:].sum() == 1.0
              ), f"observe 1 coin in grid: {player_obs[i, ..., 0]}"
  
imports: import copy
  import random
  import numpy
  from ray.rllib.examples.env.coin_game_vectorized_env import VectorizedCoinGame, AsymVectorizedCoinGame
  from ray.rllib.examples.env.tests.test_coin_game_non_vectorized_env import assert_obs_is_symmetrical
label_desc: Use image node_id 4 for calling a global function with example usage: check_obs(obs, batch_size, grid_size) without return types