hi, what is wrong with my newbie sql?

Hi, the following sql returns "10" and not "20" as would be expected.

Where is the error? This would for sure work in any programming
language, why is this different?

CREATE FUNCTION test () RETURNS INTEGER AS '

    DECLARE
        k integer;

    BEGIN
        k = 10;
        FOR k IN 1..10 LOOP
            k = k +1;
        END LOOP;

        return k;
    END;

' LANGUAGE 'plpgsql';