return types in functions

I have a function that inserts to columns into a table based upon the
result of a query from another table.  The problem is, I can't seem to
figure out what the proper return type is for this function.  Since it
doesn't retrieve anything, I can't return anything like that.  Here's the
function creation statement (without the return type):

CREATE FUNCTION insert_unknown_mfr(varchar)
RETURNS ??
AS
'INSERT INTO unknown_mfr
 SELECT DISTINCT manufacturer, drugname
 FROM drugs
 WHERE manufacturer = $1'
LANGUAGE 'sql;

Brett W. McCoy
                                         http://www.lan2wan.com/~bmccoy
-----------------------------------------------------------------------
Accuracy, n.:
    The vice of being right

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