def AddClass(self, class_name, gtfs_class):
    if class_name in self._class_mapping:
      raise problems.DuplicateMapping(class_name)
    self._class_mapping[class_name] = gtfs_class
If the server finds the new nick in conflict, the errback is called.
dataset/ETHPy150Open google/transitfeed/transitfeed/gtfsfactory.py/GtfsFactory.AddClass--crossover with--dataset/ETHPy150Open ralphm/wokkel/wokkel/test/test_muc.py/MUCClientTest.test_nickConflict