def if_not_exists(self):
        if self.model._has_counter:
            raise IfNotExistsWithCounterColumn('if_not_exists cannot be used with tables containing counter columns')
        clone = copy.deepcopy(self)
        clone._if_not_exists = True
        return clone
Check the existence of an object before insertion.
dataset/ETHPy150Open datastax/python-driver/cassandra/cqlengine/query.py/ModelQuerySet.if_not_exists