anchor.diff:        DEPTH ?DUP IF         \ IF THERE IS SOMETHING ON THE STACK
            0  DO            \ FOR EACH STACK ITEM
              ACTUAL-RESULTS I CELLS + @   \ COMPARE ACTUAL WITH EXPECTED
  -           = 0= IF S" INCORRECT RESULT: " ERROR LEAVE THEN
  +           = 0= IF S" INCORRECT RESULT" ERROR LEAVE THEN
            LOOP
         THEN
      ELSE               \ DEPTH MISMATCH
  
positive.code: 
  VARIABLE #ERRORS 0 #ERRORS !
  
  : ERROR      \ ( C-ADDR U -- ) DISPLAY AN ERROR MESSAGE FOLLOWED BY
        \ THE LINE THAT HAD THE ERROR.
     CR TYPE \ SOURCE TYPE       \ DISPLAY LINE CORRESPONDING TO ERROR
     EMPTY-STACK               \ THROW AWAY EVERY THING ELSE
     #ERRORS @ 1 + #ERRORS !
     QUIT  \ *** Uncomment this line to QUIT on an error
  ;
  
  VARIABLE ACTUAL-DEPTH         \ STACK RECORD
  CREATE ACTUAL-RESULTS 20 CELLS ALLOT
  
negative.code: $16 $d018 c! \ upper/lowercase
  test-basic-assumptions
  test-booleans
  cr s" OK" testing ;
  