code: def _peg_pose_in_hole_frame(self):
          
          # World frame
          peg_pos_in_world = self.sim.data.get_body_xpos("cylinder")
          peg_rot_in_world = self.sim.data.get_body_xmat("cylinder").reshape((3, 3))
          peg_pose_in_world = T.make_pose(peg_pos_in_world, peg_rot_in_world)
  
          # World frame
          hole_pos_in_world = self.sim.data.get_body_xpos("hole")
          hole_rot_in_world = self.sim.data.get_body_xmat("hole").reshape((3, 3))
          hole_pose_in_world = T.make_pose(hole_pos_in_world, hole_rot_in_world)
  
          world_pose_in_hole = T.pose_inv(hole_pose_in_world)
  
          peg_pose_in_hole = T.pose_in_A_to_pose_in_B(
              peg_pose_in_world, world_pose_in_hole
          )
          return peg_pose_in_hole
docs: A helper function that takes in a named data field and returns the pose of that
          object in the base frame.