PL/PGSQL question on transactions

Can you imbed BEGIN; and COMMIT; statements in the body of a pl/pgsql
function?

I am getting a parse error upon execution when I try it.

Code:

CREATE FUNCTION chitadj(integer,integer) RETURNS integer AS '
DECLARE
result integer;
oldamount integer;
BEGIN
BEGIN;
SELECT INTO oldamount chits FROM avatar
WHERE avatar_id = $1;

IF oldamount IS NULL THEN
RETURN -1;
END IF;

IF ((oldamount < abs($2)) AND ($2 < 0)) THEN
RETURN -2;
END IF;

result := oldamount + $2;
RETURN result;
COMMIT;
END;
' language 'plpgsql';

-------------------------
Dan

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