anchor.diff:  -mode(compile).
   
   -export([create/1, stop/2, start_process/2]).
  +
  +-define(DBG(Msg, Opts), case os:getenv("verbose") of
  +    false -> ok;
  +    _ -> io:format(Msg, Opts)
  +end).
   
   main([]) ->
       io:format("Usage: ./ring <number of processes>~n"),
  
positive.code:     receive
          {stop, LastPid} -> ok
      end.
  
  
  dbg(Msg, Opts) ->
      case os:getenv("verbose") of
          false -> ok;
          _ -> io:format(Msg, Opts)
      end.
  
negative.code: 
  
  start_process(0, ManagerPid) ->  % last process
      ?DBG("0!~n", []),
      %% Tell the manager we've started
      ManagerPid ! {started, self()},
      %% Wait for a stop message
  