def __virtual__():
    return 'pagerduty_escalation_policy' if 'pagerduty_util.get_resource' in __salt__ else False
:reference: https://dev.twitter.com/docs/api/1.1/post/lists/members/destroy
dataset/ETHPy150Open saltstack/salt/salt/states/pagerduty_escalation_policy.py/__virtual__--crossover with--dataset/ETHPy150Open tweepy/tweepy/tweepy/api.py/API.remove_list_member