: _
    999 SWAP        ( stop indicator )
    DUP 0 = IF '0' EXIT THEN    ( 0 is a special case )
    BEGIN
        DUP 0 = IF DROP EXIT THEN
        10 /MOD         ( r q )
        SWAP '0' + SWAP ( d q )
    AGAIN ;
: . ( n -- )
    ( handle negative )
    DUP 0< IF '-' EMIT -1 * THEN
    _
    BEGIN
        DUP '9' > IF DROP EXIT THEN  ( stop indicator )
        EMIT
    AGAIN ;
