i have downloaded the modular prosthetic limb from mujoco's models, i am new with mujoco and do not know how to use the MPL - to explain the last sentence one can goes to mujoco-py folder and then goes to example folders and from the example folder one can run body_interaction.py -i would like to ask how can i add the MPL folder to mujoco-py or mujoco folder so that i can use the MPL and even program it with python