Add pybullet env to gum

add.py

# before install pybullet with `pip install pybullet`

# source: https://github.com/bulletphysics/bullet3/blob/cbede4eb6c4b9b6d0dddf5b3964a1c7449af05d6/examples/pybullet/gym/pybullet_envs/__init__.py#L188-L191

import gym
from gym.envs.registration import registry, make, spec


def register(id, *args, **kvargs):
  if id in registry.env_specs:
    return
  else:
    return gym.envs.registration.register(id, *args, **kvargs)


register(id='HalfCheetahBulletEnv-v0',
         entry_point='pybullet_envs.gym_locomotion_envs:HalfCheetahBulletEnv',
         max_episode_steps=1000,
         reward_threshold=3000.0)

Or you can install pybullet-gym with pip install git+https://github.com/benelot/pybullet-gym
And after:

import pybulletgym