code: def step(self, action):
      done = True
      return (
          {"agent0": self.observation_space.sample()},
          {"agent0": 1.0},
          {"agent0": done, "__all__": done},
          {},
      )
  
imports: import unittest
  import ray
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.env.multi_agent_env import MultiAgentEnv
  from ray.rllib.env.wrappers.multi_agent_env_compatibility import MultiAgentEnvCompatibility
  from ray.rllib.utils.gym import try_import_gymnasium_and_gym
  from ray.tune.registry import register_env
label_desc: Use image node_id 3 for calling the MultiAgentGymnasiumOldAPI obj's underlying member method code with example usage: obj.step(action) and returns: dict,  dict,  dict,  dict