anchor.diff:      false.
   
   -spec size(Set) -> non_neg_integer() when
  -      Set :: gb_sets:set().
  +      Set :: set().
   
   size({Size, _}) ->
       Size.
  
positive.code: 
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  
  %%% gb_sets:set() in OTP 17 only.
  
  -spec empty() -> Set when
        Set :: gb_sets:set().
  
  empty() ->
      {0, nil}.
  
  -spec new() -> Set when
        Set :: gb_sets:set().
  
  new() -> empty().
  
  -spec is_empty(Set) -> boolean() when
        Set :: gb_sets:set().
  
  is_empty({0, nil}) ->
      true;
  
negative.code: %%
  %% %CopyrightBegin%
  %% 
  %% Copyright Ericsson AB 2001-2015. All Rights Reserved.
  %% 
  %% The contents of this file are subject to the Erlang Public License,
  %% Version 1.1, (the "License"); you may not use this file except in
  