class_docstr: Partially observable variant of the Pendulum gym environment.
  
  https://github.com/Farama-Foundation/Gymnasium/blob/main/gymnasium/envs/
  classic_control/pendulum.py
  
  We delete the angular velocity component of the state, so that it
  can only be solved by a memory enhanced model (policy).
code: def reset(self, *, seed=None, options=None):
      init_obs, init_info = super().reset(seed=seed, options=options)
      # init_obs is [cos(theta), sin(theta), theta-dot (angular velocity)]
      return init_obs[:-1], init_info
  
file_path: ray/python/ray/rllib/examples/env/stateless_pendulum.py
imports: from gymnasium.spaces import Box
  import numpy
  from gymnasium.envs.classic_control import PendulumEnv
label_desc: Use image node_id 3 for calling the StatelessPendulum obj's underlying member method code with example usage: obj.reset() and returns: init_obs,  init_info