anchor.diff:  
   nvl(undefined) -> $-;
   nvl(Val) -> Val.
  +
  +-spec overflow_msg(N::non_neg_integer(), datetime()) -> iolist().
  +overflow_msg(N, When) ->
  +    logplex_syslog_utils:fmt(local5,
  +                             warning,
  +                             now,
  +                             "logplex",
  +                             "logplex",
  +                             "Logplex drain buffer overflowed."
  +                             " ~p messages lost since ~s.",
  +                             [N,
  +                              datetime(When)]
  +                            ).
  +
   
   
   from_msg(Msg) when is_binary(Msg) ->
  
positive.code:          ,fmt/7
           ,rfc5424/1
           ,rfc5424/8
          ]).
  
  -type syslog_msg() :: {facility(), severity(),
                         Time::iolist(), Source::iolist(),
                         Process::iolist(), Msg::iolist()}.
  
  -export_type([ syslog_msg/0 ]).
  
  -spec to_msg(syslog_msg(), iolist() | binary()) -> iolist().
  to_msg({Facility, Severity, Time, Source, Process, Msg}, Token) ->
  
negative.code:       " ",
        Msg ].
  
  -spec datetime(datetime()) -> iolist().
  datetime(now) ->
      datetime(os:timestamp());
  datetime({_,_,_} = Now) ->
  