anchor.diff:                  callback_failures = Fails, interval_tref = Tref},
               {ok, waiting, OutCheck};
           true ->
  -            % likely a late message, or a faker
  -            {ok, suspend, InCheck#health_check{checking_pid = undefined, callback_failures = Fails}}
  +            %% likely a late message, or a faker
  +            {ok, suspend, InCheck#health_check{checking_pid = undefined,
  +                                               callback_failures = Fails}}
       end;
   
   %% message handling when in a waiting state
  
positive.code: %% of the argument list provided. A service added this way is removed like
  %% any other, using {@link service_down/1}.
  %% @see service_up/2
  -spec service_up(Id :: atom(), Pid :: pid(), Callback :: mfa(), Options :: health_opts()) -> 'ok'.
  service_up(Id, Pid, {Module, Function, Args}, Options) ->
      gen_server:call(?MODULE, {service_up, Id, Pid, {Module, Function, Args}, Options}, infinity).
  
  %% @doc Force a health check for the given service.  If the service does
  %% not have a health check associated with it, this is ignored.  Resets the
  
negative.code: -type hc_check_interval_opt() :: {check_interval, timeout()}.
  -type hc_max_callback_fails_opt() :: {max_callback_failures, non_neg_integer()}.
  -type hc_max_health_fails_opt() :: {max_health_failures, non_neg_integer()}.
  -type health_opt() :: hc_check_interval_opt() |
                        hc_max_callback_fails_opt() |
                        hc_max_health_fails_opt().
  -type health_opts() :: [health_opt()].
  %% @doc Create a service that can be declared up or down based on the
  %% result of a function in addition to usual monitoring. The function can
  