: _chk ( c --, check _sel range )
    _sel C@ DUP 0x7f > IF 0x20 _sel C! THEN
    0x20 < IF 0x7f _sel C! THEN ;
CREATE _ '0' C, ':' C, 'A' C, '[' C, 'a' C, 0xff C,
: _nxtcls
    _sel @ _ BEGIN ( c a ) C@+ 2 PICK > UNTIL ( c a )
    1- C@ NIP _sel !
;
