code: def _get_obs(self):
      return np.concatenate(
          [
              self.sim.data.qpos.flat[1:],
              self.sim.data.qvel.flat,
          ]
      )
  
file_path: gym/gym/envs/mujoco/half_cheetah.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 HalfCheetahEnv obj's underlying member method code with example usage: obj._get_obs() and returns: np