anchor.diff:  -spec byte() -> domrec(integer()).
   byte() ->
       int(0, 255).
  +
   
   %% @doc The domain of positive integers.
   %% @spec pos_integer() -> domain(pos_integer())
  
positive.code: 	{{_,H}, {_,T}} ->
  	    shrink_pair(ListDom,List,NAttempts-1);
  
  	%% either H or T changed.
  	{{HSDom,HS}, {TSDom,TS}} ->
  	    {[HSDom|TSDom], [HS|TS]}
      end.
  
negative.code: 
  %%-------------------------------------------------------------------
  %%
  %% Now, the specific domains
  %%
  %%-------------------------------------------------------------------
  
  