def AddTransferObject(self, transfer, problem_reporter=None):
    assert transfer._schedule is None, "only add Transfer to a schedule once"
    if not problem_reporter:
      problem_reporter = self.problem_reporter

    transfer_id = transfer._ID()

    if self._transfers in transfer_id:
      self.problem_reporter.DuplicateID(self._gtfs_factory.Transfer._ID_COLUMNS,
                                        transfer_id,
                                        type=problems_module.TYPE_WARNING)
      # Duplicates are still added, while not prohibited by GTFS.

    transfer._schedule = weakref.proxy(self)  # See weakref comment at top
    self.AddTableColumns('transfers', transfer._ColumnNames())
    self._transfers[transfer_id].append(transfer)
dataset/ETHPy150Open google/transitfeed/transitfeed/schedule.py/Schedule.AddTransferObject/swapped operands of `in`