anchor.diff:  
   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
  -;
  +: ERROR      \ ( C-ADDR U -- ) DISPLAY AN ERROR MESSAGE
  +testing QUIT ;
   
   VARIABLE ACTUAL-DEPTH         \ STACK RECORD
   CREATE ACTUAL-RESULTS 20 CELLS ALLOT
  
positive.code: $16 $d018 c! \ upper/lowercase
  test-basic-assumptions
  test-booleans
  s" ok" type ;
  
negative.code:       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
           LOOP
        THEN
     ELSE               \ DEPTH MISMATCH
  