<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_available_ip6(self, id_network6):
 """ Get a available IP in Network ipv6 :param id_network6: Network ipv6 identifier. Integer value and greater than zero. :return: Dictionary with the following structure: :: {'ip6': {'ip6': < available_ip6 >}} :raise IpNotAvailableError: Network dont have available IP. :raise NetworkIPv4NotFoundError: Network was not found. :raise UserNotAuthorizedError: User dont have permission to get a available IP. :raise InvalidParameterError: Network ipv6 identifier is none or invalid. :raise XMLError: Networkapi failed to generate the XML response. :raise DataBaseError: Networkapi failed to access the database. """


        if not is_valid_int_param(id_network6):
            raise InvalidParameterError(
                u'Network ipv6 identifier is invalid or was not informed.')

        url = 'ip/availableip6/' + str(id_network6) + "/"

        code, xml = self.submit(None, 'GET', url)

        return self.response(code, xml)