Query builder: How to multiply a selected value by -1?

[Robert-M-Muench]

I'm trying to build a query where the final sum is multiplied by -1, but I don't know where to put the * -1:

vg.Query
        .from("data")
	.select({sumA: vg.sum("A")})
	.where(vg.lt("A",0))

That's the SQL string I get:

SELECT SUM("A")::DOUBLE AS "sumA" FROM "data" WHERE ("A" < 0)

and this is what I would like to get:

SELECT SUM("A")::DOUBLE * -1 AS "sumA" FROM "data" WHERE ("A" < 0)