class_docstr: A reward shaping wraper
class_docstr_tok: ["A","reward","shaping","wraper"]
code: def reward_shaping(self, state_desc, r2_reward, done, action):
      target_vel = math.sqrt(
          state_desc["target_vel"][0] ** 2
          + state_desc["target_vel"][2] ** 2
      )
      if state_desc["target_vel"][0] < 0:
          target_vel = -target_vel
  
      info = {
          "shaping_reward": r2_reward,
          "target_vel": target_vel,
          "r2_reward": r2_reward,
      }
      return info
  
imports: import abc
  import copy
  import gym
  import math
  import numpy
  from collections import OrderedDict
  from osim.env import ProstheticsEnv
  from parl.utils import logger
label_desc: Use image node_id 2 for calling the ForwardReward obj's underlying member method code with example usage: obj.reward_shaping(state_desc, r2_reward, done, action) and returns: info