def ppo_cli_args(parser):
    """
    Add standard PPO arguments to an ArgumentParser.

    This is useful for scripts that run training.
    """
    parser.add_argument('--ppo-lr', help='Adam learning rate', default=
        0.0003, type=float)
    parser.add_argument('--ppo-horizon', help='PPO horizon', default=128,
        type=int)
    parser.add_argument('--ppo-iters', help='PPO iterations', default=16,
        type=int)
    parser.add_argument('--ppo-epsilon', help='PPO clipping fraction',
        default=0.1, type=float)
    parser.add_argument('--ppo-discount', help='PPO discount factor',
        default=0.99, type=float)
    parser.add_argument('--ppo-lambda', help='PPO lambda', default=0.95,
        type=float)
    parser.add_argument('--ppo-entropy', help='PPO entropy bonus', default=
        0.01, type=float)
    parser.add_argument('--ppo-reward-scale', help='PPO reward scale',
        default=1.0, type=float)
    parser.add_argument('--save-path', help='path to PPO save file',
        default='ppo_agent.pkl')
    parser.add_argument('--save-interval', help='iterations per save',
        default=5, type=int)
