code: def register_env(name, env_creator):
      
  
      if not isinstance(env_creator, FunctionType):
          raise TypeError("Second argument must be a function.", env_creator)
      _global_registry.register(ENV_CREATOR, name, env_creator)
docs: Register a custom environment for use with RLlib.
  
      Args:
          name (str): Name to register.
          env_creator (obj): Function that creates an env.