code: def hwvtep_add_loopback_interface(self, **kwargs):
          
          name = kwargs.pop('name')
          id = kwargs.pop('int_id')
          ip_args = dict(name=name, loopback_id=id)
          method_name = 'overlay_gateway_ip_interface_loopback_loopback_id'
          method_class = self._brocade_tunnels
          gw_attr = getattr(method_class, method_name)
          config = gw_attr(**ip_args)
          output = self._callback(config)
          return output
docs: Add loopback interface to the overlay-gateway
  
          Args:
              name  (str): gateway-name
              int_id (int): loopback inteface id
              callback (function): A function executed upon completion of the
                   method.
  
          Returns:
             Return value of `callback`.
  
          Raises:
              None