code: def viewer_setup(self):
      assert self.viewer is not None
      self.viewer.cam.trackbodyid = 0
  
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 3 for calling the ReacherEnv obj's underlying member method code with example usage: obj.viewer_setup() without return types