class_docstr: Simple Env that yields a ts counter as observation (0-based).
  
  Actions have no effect.
  The episode length is always 15.
  Reward is always: current ts % 3.
code: def _get_obs(self):
      return np.array([self.i], dtype=np.float32)
  
file_path: ray/python/ray/rllib/examples/env/debug_counter_env.py
imports: import gymnasium
  import numpy
  from ray.rllib.env.multi_agent_env import MultiAgentEnv
label_desc: Use image node_id 4 for calling the DebugCounterEnv obj's underlying member method code with example usage: obj._get_obs() and returns: np