code: def test_cast_observation(env_id, dtype):
      env = pfrl.wrappers.CastObservation(gym.make(env_id), dtype=dtype)
      rtol = 1e-3 if dtype == np.float16 else 1e-7
  
      obs = env.reset()
      assert env.original_observation.dtype == np.float64
      assert obs.dtype == dtype
      np.testing.assert_allclose(
          env.original_observation, obs, rtol=rtol
      )
  
      obs, r, done, info = env.step(env.action_space.sample())
  
      assert env.original_observation.dtype == np.float64
      assert obs.dtype == dtype
      np.testing.assert_allclose(
          env.original_observation, obs, rtol=rtol
      )
  
imports: import gym
  import numpy
  import pytest
  import pfrl
label_desc: Use image node_id 1 for calling a global function with example usage: test_cast_observation(env_id, dtype) without return types