I would like to execute a couple of select queries using UNION DISTINCT statement.

As ClickHouse docs says I should provide ALL or DISTINCT keywords, or set union_default_mode previously.
But I can not find possibility to provide some of keywords. Clickhouse-sqlalchemy docs mentions about UNION only in this section and provide example of using sqlalchemy built-in expression union_all. It`s usefull but how to execute UNION DISTINCT?

I see only way to set union_default_mode before my query. Does exist way to add keword to UNION with some of sqlalchemy tools, or probably I missed something in clickhouse-sqlalchemy documentation?