-spec adding_handler(Config) -> {ok, Config} | {error, Reason}
                        when Config :: logger:handler_config(), Reason :: term().

-spec changing_config(SetOrUpdate, OldConfig, NewConfig) -> {ok, Config} | {error, Reason}
                         when
                             SetOrUpdate :: set | update,
                             OldConfig :: logger:handler_config(),
                             NewConfig :: logger:handler_config(),
                             Config :: logger:handler_config(),
                             Reason :: term().

-spec filesync(Name) -> ok | {error, Reason}
                  when Name :: atom(), Reason :: handler_busy | {badarg, term()}.

-spec filter_config(Config) -> Config when Config :: logger:handler_config().

-spec log(LogEvent, Config) -> ok when LogEvent :: logger:log_event(), Config :: logger:handler_config().

-spec removing_handler(Config) -> ok when Config :: logger:handler_config().