A logger.
rust
let mut app = Appender::new("test", "console://;line=[%y%m%d-%H:%M:%S.%U];flush=true").unwrap();
app.verb("verb log");
app.info("info log");
app.debug("debug log");
app.warn("warn log");
app.except("except log");
app.fail("fail log");
app.fatal("fatal log");