anchor.diff:  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
  
positive.code: T{ 1S 1S XOR -> 0S }T ;
  
  : start
  test-basic-assumptions
  test-booleans
  s" ok" type ;
  
negative.code: \    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 )
  