def datetime_to_timestamp(dateTime):
    diff = as_utc(dateTime) - epoch_utc
    return diff.total_seconds()
:reference: https://dev.twitter.com/rest/reference/get/direct_messages
dataset/ETHPy150Open gbeced/pyalgotrade/pyalgotrade/utils/dt.py/datetime_to_timestamp--crossover with--dataset/ETHPy150Open tweepy/tweepy/tweepy/api.py/API.direct_messages