def add_to_index_or_fail(self, cls, index, key, value, entity):
        query = "uniqueness=create_or_fail"
        return self._add_to_index(cls, index, key, value, entity, query)
Add an existing node or relationship uniquely to an index, failing
dataset/ETHPy150Open nigelsmall/py2neo/py2neo/ext/batman/batch.py/ManualIndexWriteBatch.add_to_index_or_fail