def subset_check(subset=None, set_=None):
    """Return True/False depending on if set is subset of larger set.

    If subset - set_ != 0, then subset contains keys that are not in
    set_.

    set_ is our 'allowed keys' in this use case.

    Another use case is testing if a required subset exists in set_.
    For example, looking for keys that are REQUIRED to be in the config.

    :param subset: The set we are checking to see if it is a subset of
        set_.
    :param set_: The set_ being tested against.

    :return: True if subset, False if it isn't.
    """
    if subset - set_:
        return False
    return True
