Adding comments to generated SQL

Is there a way to construct SQL statement in the usual way, then add a an SQL comment with custom content, to the query before sending it to the database? Ideally this comment would be able to be added at any point in the construction process; for example, I could add a comment to a `filter_` and it would show up above the `where` in SQL. It would also be acceptable to only be able to add the comment right before `runBeamPostgres` or `runSelect*`; Maybe a different version of these functions that would take a comment string.