class_docstr: Env wrapper that keeps tracks of total raw episode rewards, length of raw episode rewards for evaluation.
      
class_docstr_tok: ["Env","wrapper","that","keeps","tracks","of","total","raw","episode","rewards",",","length","of","raw","episode","rewards","for","evaluation","."]
code: def __init__(self, env):
      super().__init__(env)
      self.tstart = time.time()
      self.rewards = None
  
imports: import numpy
  import gym
  import time
  from parl.env.compat_wrappers import CompatWrapper
label_desc: Use image node_id 1 to create a new MonitorEnv object from inherited base classes: gym with example: obj = MonitorEnv(env)