code: def ref(self, xml_id):
          
          model, id_ = self._odoo.execute(
              'ir.model.data', 'xmlid_to_res_model_res_id', xml_id, True)
          return self[model].browse(id_)
docs: Return the record corresponding to the given `xml_id` (also called
          external ID).
          Raise an :class:`RPCError <odoorpc.error.RPCError>` if no record
          is found.
  
          .. doctest::
  
              >>> odoo.env.ref('base.lang_en')
              Recordset('res.lang', [1])
  
          :return: a :class:`odoorpc.models.Model` instance (recordset)
          :raise: :class:`odoorpc.error.RPCError`