anchor.diff:  
   %% Arithmetic
   
  --spec range_add(#range{}, #range{}) -> #range{}.
  +-spec range_add(range(), range()) -> range().
   
   range_add(Range1, Range2) ->
     NewMin = inf_add(range__min(Range1), range__min(Range2)),
  
positive.code: 
  other_inf(O1, O2) -> O1 and O2.
  
  -spec sup([#range{},...]) -> #range{}.
  
  sup([R]) ->
    R;
  sup([R1,R2|Rest]) ->
    sup([sup(R1, R2)|Rest]).
  
  -spec sup(#range{}, #range{}) -> #range{}.
  
  sup(#range{range=R1,other=O1}, #range{range=R2,other=O2}) -> 
    #range{range=range_sup(R1,R2), other=other_sup(O1,O2)}.
  
negative.code:     end,
    range_init(MinMax, false).
  
  -spec range_bnot(range()) -> range().
  
  range_bnot(Range) ->
    Minus_one = range_init({-1,-1}, false),
  