class_docstr: Variant of CartPoleEnv with velocity information removed. This task requires memory to solve.
code: def __init__(self):
      super(CartPoleNoVelEnv, self).__init__()
      high = np.array(
          [
              self.x_threshold * 2,
              self.theta_threshold_radians * 2,
          ]
      )
      self.observation_space = spaces.Box(-high, high, dtype=np.float32)
  
imports: import os
  from gym.envs.classic_control import CartPoleEnv
  from gym.wrappers.time_limit import TimeLimit
  from gym import spaces
  import numpy
  import pytest
  from stable_baselines import A2C, ACER, ACKTR, PPO2, bench
  from stable_baselines.common.policies import MlpLstmPolicy, LstmPolicy
  from stable_baselines.common.vec_env import SubprocVecEnv
  from stable_baselines.common.vec_env.vec_normalize import VecNormalize
  from stable_baselines.common.math_util import safe_mean
  from stable_baselines.common.evaluation import evaluate_policy
label_desc: Use image node_id 1 to create a new CartPoleNoVelEnv object from inherited base classes: CartPoleEnv with example: obj = CartPoleNoVelEnv()