@classmethod
def remove_verbs(cls, *verbs):
    """Remove verbs from this shell.

        :param str verbs: A sequence of verbs to remove
        :returns None:

        """
    for verb in verbs:
        command = cls._verbs.get(verb)
        if command:
            del cls._verbs[verb]
            verb = verb[:-1]
            while verb:
                if cls._verbs.get(verb) is command:
                    del cls._verbs[verb]
                verb = verb[:-1]
