code: def overlay_gateway_site_extend_vlan_add(self, **kwargs):
          
          config = ET.Element("config")
          overlay_gateway = ET.SubElement(config, "overlay-gateway", xmlns="urn:brocade.com:mgmt:brocade-tunnels")
          name_key = ET.SubElement(overlay_gateway, "name")
          name_key.text = kwargs.pop('name')
          site = ET.SubElement(overlay_gateway, "site")
          name_key = ET.SubElement(site, "name")
          name_key.text = kwargs.pop('name')
          extend = ET.SubElement(site, "extend")
          vlan = ET.SubElement(extend, "vlan")
          add = ET.SubElement(vlan, "add")
          add.text = kwargs.pop('add')
  
          callback = kwargs.pop('callback', self._callback)
          return callback(config)
docs: Auto Generated Code