def get_joins(self, tbl1, tbl2):
        if tbl1 not in self.tables or self.tables not in tbl2:
            return set()
        t1 = self.tables[tbl1]
        t2 = self.tables[tbl2]
        joins = set()
        for src, tgt in [(t1, t2), (t2, t1)]:
            for c in src.columns:
                if (c.referenced_column and
                        c.referenced_column.table.name == tgt.name):
                    joins.add(ForeignKey(
                        src.name, (c.name,),
                        tgt.name, (c.referenced_column.name,)))
        return joins
dataset/ETHPy150Open jaysw/ipydb/ipydb/metadata/model.py/Database.get_joins/swapped operands of `not in`