def __set__(self, instance, value):
        field = instance._fields[self.name]
        value = field.pre_setattr(value)
        instance._data[self.name] = value
Should have a unique set of contests for all elections
dataset/ETHPy150Open schematics/schematics/schematics/models.py/FieldDescriptor.__set__--crossover with--dataset/ETHPy150Open openelections/openelections-core/openelex/us/md/validate/__init__.py/validate_unique_contests