basics on User Defined Functions

Is this the correct way to return values in a record from a UDF in 7.4.+ ?

Is it ok to modify the arguments as in 'arg_int'?

-- return type should be RECORD
--
CREATE OR REPLACE FUNCTION test_function( int )
RETURNS RECORD AS '
DECLARE

    arg_int               ALIAS FOR $1;

    var_record_out          record;
    var_message_out         text;

BEGIN

    var_message_out := ''This was successful'';
    arg_int := rg_int * 3;

    SELECT INTO var_record_out
        :arg_int AS intX3,
        :var_message_out AS message;
    RETURN var_record_out;
END;
' LANGUAGE 'plpgsql';