anchor.diff:      end.
   
   
  --spec start_timer(server(), pos_integer(), pid(), term()) -> reference().
  +-spec start_timer(timeserver(), pos_integer(), pid(), term()) -> reference().
   start_timer(Server, Time, Dest, Msg) ->
       case Server of
           native -> erlang:start_timer(Time, Dest, Msg);
  
positive.code: 
  %% api functions
  -export([start_link/1,
           send_after/4,
           start_timer/4,
           cancel/2,
  
negative.code: 
  
  %% Return the number of milliseconds that passed
  -spec step(timeserver()) -> pos_integer().
  step(Server) ->
      case Server of
          native -> error(badarg);
  