code: def step(self, a):
      vec = self.get_body_com("fingertip") - self.get_body_com("target")
      reward_dist = -np.linalg.norm(vec)
      reward_ctrl = -np.square(a).sum()
      reward = reward_dist + reward_ctrl
  
      self.do_simulation(a, self.frame_skip)
      if self.render_mode == "human":
          self.render()
  
      ob = self._get_obs()
      return (
          ob,
          reward,
          False,
          False,
          dict(reward_dist=reward_dist, reward_ctrl=reward_ctrl),
      )
  
file_path: gym/gym/envs/mujoco/reacher.py
imports: import numpy
  from gym import utils
  from gym.envs.mujoco import MuJocoPyEnv
  from gym.spaces import Box
label_desc: Use image node_id 2 for calling the ReacherEnv obj's underlying member method code with example usage: obj.step(a) and returns: ob,  reward,  False,  False,  dict