anchor.diff:  subscribe(To,Channel) ->
       Member = pg2:get_members(To),
       case Member of
  -	[To|_]->pg2:join(N),
  +	[To|_]->pg2:join(Channel),
   		self()!subscribed;
   	{error,_} ->self()!error
       end.
  
positive.code: 	[Channel|_]->Channel!Msg;
  	{error,_}-> self()!error
      end.
  ok.
  
negative.code: -export([add_pid/2]).
  -export([deliver_message/2]).
  -export([subscribe/2]).
  -export([publish/2]).
  
  add_pid(Pid,Name)->
  Member = pg2:get_members(Name),
  