code: def merge_objects(self, mujoco_objects):
          
          self.mujoco_objects = mujoco_objects
          self.objects = {}  # xml manifestation
          self.max_horizontal_radius = 0
          for obj_name, obj_mjcf in mujoco_objects.items():
              self.merge_asset(obj_mjcf)
              # Load object
              obj = obj_mjcf.get_collision(name=obj_name, site=True)
              obj.append(new_joint(name=obj_name, type="free", damping="0.0005"))
              self.objects[obj_name] = obj
              self.worldbody.append(obj)
  
              self.max_horizontal_radius = max(
                  self.max_horizontal_radius, obj_mjcf.get_horizontal_radius()
              )
docs: Adds physical objects to the MJCF model.