anchor.diff:  
   health_fsm({'EXIT', Pid, Cause}, Service, #health_check{checking_pid = Pid} = InCheck) ->
       lager:error("health check process for ~p error'ed:  ~p", [Service, Cause]),
  -    {M,F,A} = InCheck#health_check.callback,
       Fails = InCheck#health_check.callback_failures + 1,
       if
           Fails == InCheck#health_check.max_callback_failures ->
  
positive.code:     ok;
  
  % fallthrough handling
  health_fsm(Msg, Service, Health) ->
      {ok, Health}.
  
  start_health_check(Service, #health_check{checking_pid = undefined} = CheckRec) ->
  
negative.code:     },
      {ok, OutCheck};
  
  health_fsm(remove, _Service, #health_check{state = suspend}) ->
      ok;
  
  %% message handling when checking state
  health_fsm(suspend, _Service, #health_check{state = checking} = InCheck) ->
      #health_check{checking_pid = Pid} = InCheck,
      erlang:erase(Pid),
      {ok, InCheck#health_check{state = suspend, checking_pid = undefined}};
  