code: def test_env(self):
      env = CliffWalkingWallEnv()
      obs, info = env.reset()
      # Starting position
      self.assertEqual(obs, 36)
      # Left, Right, and Down are no-ops
      obs, _, _, _, _ = env.step(ACTION_LEFT)
      self.assertEqual(obs, 36)
      obs, _, _, _, _ = env.step(ACTION_DOWN)
      self.assertEqual(obs, 36)
      obs, _, _, _, _ = env.step(ACTION_RIGHT)
      self.assertEqual(obs, 36)
  
      # Up and Down returns to starting position
      obs, _, _, _, _ = env.step(ACTION_UP)
      self.assertEqual(obs, 24)
      obs, _, _, _, _ = env.step(ACTION_DOWN)
      self.assertEqual(obs, 36)
      obs, _, _, _ = env.step(ACTION_DOWN)
      self.assertEqual(obs, 36)
  
      # Going down at the wall is a no-op
      env.step(ACTION_UP)
      obs, _, _, _ = env.step(ACTION_RIGHT)
      self.assertEqual(obs, 25)
      obs, _, _, _ = env.step(ACTION_DOWN)
      self.assertEqual(obs, 25)
  
      # Move all the way to the right wall
      for _ in range(10):
          env.step(ACTION_RIGHT)
      obs, rew, done, truncated, _ = env.step(ACTION_RIGHT)
      self.assertEqual(obs, 35)
      self.assertEqual(rew, -1)
      self.assertEqual(done, False)
  
      # Move to goal
      obs, rew, done, truncated, _ = env.step(ACTION_DOWN)
      self.assertEqual(obs, 47)
      self.assertEqual(rew, 10)
      self.assertEqual(done, True)
  
imports: from ray.rllib.examples.env.cliff_walking_wall_env import CliffWalkingWallEnv, ACTION_UP, ACTION_RIGHT, ACTION_DOWN, ACTION_LEFT
  import unittest
label_desc: Use image node_id 1 for calling the TestCliffWalkingWallEnv obj's underlying member method code with example usage: obj.test_env() without return types