code: def block_user(self, username, domain):
          
          self.set_password(username, domain, self.get_random_password())
docs: Block the specified user.
  
          The default implementation calls :py:func:`~xmpp_backends.base.XmppBackendBase.set_password` with a
          random password.
  
          :param username: The username of the user.
          :type  username: str
          :param   domain: The domain of the user.
          :type    domain: str