code: def get_instance(self, payload):
          
          return AvailableAddOnExtensionInstance(
              self._version,
              payload,
              available_add_on_sid=self._solution['available_add_on_sid'],
          )
docs: Build an instance of AvailableAddOnExtensionInstance
  
          :param dict payload: Payload response from the API
  
          :returns: twilio.rest.preview.marketplace.available_add_on.available_add_on_extension.AvailableAddOnExtensionInstance
          :rtype: twilio.rest.preview.marketplace.available_add_on.available_add_on_extension.AvailableAddOnExtensionInstance