def get_subclasses(*args):
    """Gets the subclasses of the parameters.

    Parameters
    ----------
    *args : :class:`type`
        The types to get the subclasses of.

    Returns
    -------
    :class:`set`
        The subclasses of ``*args``.
    """

    ret = set()

    for arg in args:
        tmp = set(arg.__subclasses__())
        tmp |= get_subclasses(*tmp)
        ret |= tmp

    return ret