anchor.diff:  
   -type queue_key()        :: {Src :: comm:mypid(), Dest :: comm:mypid()}.
   -type delay_queue_key()  :: {Dest :: comm:mypid()}.
  --type msg_queues()       :: [{queue_key(), queue()}].
  --type msg_delay_queues() :: [{delay_queue_key(), queue()}].
  +-type msg_queues()       :: [queue_key()].
  +-type msg_delay_queues() :: [delay_queue_key()].
   
   -record(state,
           {msg_queues              = ?required(state, msg_queues)
  
positive.code: update_queue_in_list_of_queues(Key, Q, Queues) ->
      case queue:is_empty(Q) of
          true ->
              lists:keydelete(Key, 1, Queues);
          false ->
              Tuple = {Key, Q},
              lists:keyreplace(Key, 1, Queues, Tuple)
      end.
  
negative.code:         (queue_key(), {local | global, comm:message()}, msg_queues()) -> msg_queues().%;
          %(delay_queue_key(), comm:message(), msg_delay_queues()) -> msg_delay_queues().
  add_to_list_of_queues(Key, M, Queues) ->
      case erlang:get(Key) of
          undefined ->
              _ = erlang:put(Key, queue:from_list([M])),
              [Key | Queues];
          Queue ->
              _ = erlang:put(Key, queue:in(M, Queue)),
              Queues
      end.
  
  -spec update_queue_in_list_of_queues
  