class_docstr: Example of a custom env with a complex, structured observation.
  
  The observation is a list of players, each of which is a Dict of
  attributes, and may further hold a list of items (categorical space).
  
  Note that the env doesn't train, it's just a dummy example to show how to
  use spaces.Repeated in a custom model (see CustomRPGModel below).
code: def step(self, action):
      return self.observation_space.sample(), 1, True, False, {}
  
file_path: ray/python/ray/rllib/examples/env/simple_rpg.py
imports: import gymnasium
  from gymnasium.spaces import Discrete, Box, Dict
  from ray.rllib.utils.spaces.repeated import Repeated
label_desc: Use image node_id 3 for calling the SimpleRPG obj's underlying member method code with example usage: obj.step(action) and returns: self,  int,  True,  False,  dict