class_docstr: Bring rewards to a reasonable scale for PPO.
  This is incredibly important and effects performance
  drastically.
class_docstr_tok: ["Bring","rewards","to","a","reasonable","scale","for","PPO",".","This","is","incredibly","important","and","effects","performance","drastically","."]
code: def reward(self, reward):
      return reward * self.scale
  
imports: from collections import deque
  import cv2
  from .atari_wrappers import WarpFrame, ClipRewardEnv, FrameStack, ScaledFloatFrame
  from .wrappers import TimeLimit
  import numpy
  import gym
label_desc: Use image node_id 2 for calling the RewardScaler obj's underlying member method code with example usage: obj.reward(reward) and returns: unknown