anchor.diff:  
   update(Key, Value, Pid) ->
     gen_server:call(Pid, {update, Key, Value}, infinity).
  +  
  +updatea(Key, Value, Pid) ->
  +  gen_server:cast(Pid, {update, Key, Value}).
   
   equals(A, B) ->
     gen_server:call(A, hash) == gen_server:call(B, hash).
  
positive.code: -include("dmerkle.hrl").
  
  %% API
  -export([open/1, open/2, equals/2, get_tree/1, count/2, count_trace/2, update/3, delete/2, leaves/1, find/2, visualized_find/2, key_diff/2, close/1, scan_for_empty/1, swap_tree/2]).
  
  %% gen_server callbacks
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  
negative.code: 
  delete(Key, Tree) ->
    gen_server:call(Tree, {delete, Key}).
    
  deletea(Key, Tree) ->
    gen_server:cast(Tree, {delete, Key}).
  
  key_diff(TreeA, TreeB) ->
    gen_server:call(TreeA, {key_diff, TreeB}).
  