def listify_string(something):
    """Takes *something* and make it a list.

    *something* is either a list of strings or a string, in which case the
    function returns a list containing the string.
    If *something* is None, an empty list is returned.
    """
    if isinstance(something, (str, six.text_type)):
        return [something]
    elif something is not None:
        return list(something)
    else:
        return list()