anchor.diff:  
   post(Feed, Text) ->
       gen_server:call(?MODULE, {post, Feed, Text}).
  +
  +comment(PostID, Text) ->
  +    gen_server:call(?MODULE, {comment, PostID, Text}).
   
   is_logged_in() ->
       gen_server:call(?MODULE, {is_logged_in}).
  
positive.code:     Response = jiffy:decode(Data, [return_maps]),
      #{<<"posts">> := Posts} = Response,
      Posts.
  
negative.code:          get_posts/1,
           login/0,
           post/2,
           comment/2,
           is_logged_in/0
          ]).
  
  