: ?DO
   postpone 2dup  postpone =
   postpone if  postpone 2drop
   postpone else  1  postpone do ;
immediate

: DO  0  postpone do ; immediate

: ?resolve-do \ factor of loop & +loop
  if  postpone then  then ;

: LOOP
  postpone loop  ?resolve-do
; immediate

: +LOOP
  postpone +loop  ?resolve-do
; immediate