code: def fetch(self):
          
          params = values.of({})
  
          payload = self._version.fetch(
              'GET',
              self._uri,
              params=params,
          )
  
          return AssignedAddOnInstance(
              self._version,
              payload,
              account_sid=self._solution['account_sid'],
              resource_sid=self._solution['resource_sid'],
              sid=self._solution['sid'],
          )
docs: Fetch a AssignedAddOnInstance
  
          :returns: Fetched AssignedAddOnInstance
          :rtype: twilio.rest.api.v2010.account.incoming_phone_number.assigned_add_on.AssignedAddOnInstance