Hi! I'm just starting to use mujoco to simulate UR5 with RL eventually. I've researched RL with UR5 in gazebo and gym. However, since my research now need contact and friction dynamics, I decided to use mujoco. Is there any example that I can see to use mujoco? I just need to know how to load model and get state and visualize the robot. I've searched and found ur5.xml and that there are several other robot models such as 'arm with gripper' and 'baxter'. Could you help me, please?