Run the ``list_users`` command and return a list of tuples describing
        the users.

        :return:
            A list of 2-element tuples. The first element is the username, the
            second a list of tags for the user.

def list_users(self):
        """
        Run the ``list_users`` command and return a list of tuples describing
        the users.

        :return:
            A list of 2-element tuples. The first element is the username, the
            second a list of tags for the user.
        """
        lines = output_lines(self.exec_rabbitmqctl_list('users'))
        return [_parse_rabbitmq_user(line) for line in lines]