class_docstr: Modified version of the CliffWalking environment from Farama-Foundation's
  Gymnasium with walls instead of a cliff.
  
  ### Description
  The board is a 4x12 matrix, with (using NumPy matrix indexing):
  - [3, 0] or obs==36 as the start at bottom-left
  - [3, 11] or obs==47 as the goal at bottom-right
  - [3, 1..10] or obs==37...46 as the cliff at bottom-center
  
  An episode terminates when the agent reaches the goal.
  
  ### Actions
  There are 4 discrete deterministic actions:
  - 0: move up
  - 1: move right
  - 2: move down
  - 3: move left
  You can also use the constants ACTION_UP, ACTION_RIGHT, ... defined above.
  
  ### Observations
  There are 3x12 + 2 possible states, not including the walls. If an action
  would move an agent into one of the walls, it simply stays in the same position.
  
  ### Reward
  Each time step incurs -1 reward, except reaching the goal which gives +10 reward.
code: def __init__(self, seed=42) -> None:
      self.observation_space = spaces.Discrete(48)
      self.action_space = spaces.Discrete(4)
      self.observation_space.seed(seed)
      self.action_space.seed(seed)
  
imports: import gymnasium
  from gymnasium import spaces
label_desc: Use image node_id 1 to create a new CliffWalkingWallEnv object from inherited base classes: gym with example: obj = CliffWalkingWallEnv(seed)