anchor.diff:      begin
           2dupxor
       while
  -        dup c@ c,
  -        1+
  +        count c,
       repeat
       2drop
       align
  
positive.code:     \ skip all characters satisfying xt ( c -- f )
      >r
      BEGIN
      over c@ r@ execute
      over 0<> and
      WHILE
  	1/string
      REPEAT
      r> drop ;
  
  
negative.code: \ From Forth200x - public domain
  
  : isspace? ( c -- f )
      h# 21 u< ;
  
  : isnotspace? ( c -- f )
      isspace? 0= ;
  