code: def read_multi_vars(self, items):
          
          result = self.library.Cli_ReadMultiVars(self.pointer, byref(items),
                                                  c_int32(len(items)))
          check_error(result, context="client")
          return result, items
docs: This function read multiple variables from the PLC.
  
          :param items: list of S7DataItem objects
          :returns: a tuple with the return code and a list of data items