anchor.diff:           ,name/1
            ,cache/1
            ,delete/1
  +         ,delete_by_channel/1
            ,new/3
            ,new/2
            ,new_unique_token_id/0
  
positive.code: 
  -export([lookup/1
           ,lookup_by_channel/1
          ]).
  
  -export([id/1
  
negative.code: new_token_id() ->
      iolist_to_binary(["t.", uuid:to_iolist(uuid:v4())]).
  
  lookup_by_channel(ChannelId) ->
      lists:flatmap(fun (Id) ->
                            ets:lookup(?TOKEN_TAB, Id)
                    end,
                    lookup_ids_by_channel(ChannelId)).
  
  store(#token{id=Token,
               channel_id=ChannelId,
  