anchor.diff:  	next,
   tend-code
   
  -tcode R@	\ TODO test
  +tcode R@
   	0 rsp x8 ld,
   	-8 dsp dsp addi,
   	0 dsp x8 sd,
  
positive.code: : ~BEGIN	there ;
  : ~WHILE	~IF swap ;
  : ~REPEAT	[t'] branch t, t, ~THEN ;
  : ~FOR		[t'] (dofor) t, ~BEGIN ;
  : ~NEXT		[t'] ?next t, t, ;
  : ~AHEAD	[t'] branch t, there 0 t, ;
  : ~AFT		drop ~AHEAD ~BEGIN swap ;
  
negative.code: \ to a corresponding FOR-loop's entry is NOT taken.  It
  \ is compiled by NEXT.
  \ 
  \ (dofor) moves a count to the return stack, as-is,
  \ as per the semantics for a FOR-loop.  It is compiled
  \ by FOR.  Because it doesn't pre-decrement the count,
  \ be aware that you should pre-decrement as needed.
  \ E.g., 8 FOR R@ . NEXT will produce the output
  \ 8 7 6 5 4 3 2 1 0, *not* 7 6 5 4 3 2 1 0.
  tcode ?next
  	0 rsp x9 ld,
  	-1 x9 x9 addi,
  