def get_account_age_in_days(numpy_time_difference):
    """
    Args
        numpy_time_difference (numpy timedelta): a numpy timedelta object
        that is the difference between the user's account creation date
        and the date of their most recent tweet
    Return
        account_age (int)
    """
    return int(numpy_time_difference/1000000000/60/60/24)+1