anchor.diff:  \    IF DUP >R TYPE CR R> >IN !
   \    ELSE >IN ! DROP [CHAR] * EMIT
   \    THEN ;
  +: testing type cr ;
   
   \ ====== Imported from core test suite
   
   : BITSSET? IF 0 0 ELSE 0 THEN ;
   : test-basic-assumptions
  +s" BASIC ASSUMPTIONS" testing
   T{ -> }T               \ START WITH CLEAN SLATE
   \ ( TEST IF ANY BITS ARE SET; ANSWER IN BASE 1 )
   T{  0 BITSSET? -> 0 }T      ( ZERO IS ALL BITS CLEAR )
  
positive.code: T{ 1S 1S XOR -> 0S }T ;
  
  : start
  test-basic-assumptions
  test-booleans
  s" ok" type ;
  
negative.code: ffff CONSTANT 1S
  
  : test-booleans
  s" BOOLEANS: INVERT AND OR XOR" testing
  T{ 0 0 AND -> 0 }T
  T{ 0 1 AND -> 0 }T
  T{ 1 0 AND -> 0 }T
  