is this possible in plpgsql ?

I have 1 function in pg 7.3.2.

txt string have 1,2,3,.. and i would like to be similar like if 3 in
(1,2,3..) then, but IF 3 in (''''||txt||'''') THEN doesn't work.
There is possible to this or not ?

CREATE OR REPLACE FUNCTION rek2(INT8) RETURNS text AS '
DECLARE
i INT8;
BEGIN
txt := '''';
for i in 1 .. 10 loop
txt := txt||i||'','';
END loop;
txt := txt||''0'';
IF 3 in (''''||txt||'''') THEN
raise notice ''yep'';
END IF;
RETURN txt;
END;
' LANGUAGE 'plpgsql';

--
"Nieobecni nie mają racji"

Marcin Winkler