def _query_conjunction(self, queries):
        query_ops = set()
        combined_query = {}
        for query in queries:
            ops = set(query.keys())
            # Make sure that the same operation isn't applied more than once
            # to a single field
            intersection = ops.intersection(query_ops)
            if intersection:
                raise DuplicateQueryConditionsError()

            query_ops.update(ops)
            combined_query.update(copy.deepcopy(query))
        return combined_query
Merges query dicts - effectively &ing them together.
dataset/ETHPy150Open MongoEngine/mongoengine/mongoengine/queryset/visitor.py/SimplificationVisitor._query_conjunction