// Handle handles the Record.
// It will only be called if Enabled returns true.
// Handle methods that produce output should observe the following rules:
//   - If r.Time is the zero time, ignore the time.
//   - If an Attr's key is the empty string, ignore the Attr.
Handle(r Record) error

slog.SetDefault(slog.New(slog.HandlerOptions{
  Level: slog.LevelWarn,
}.NewTextHandler(os.Stdout)))

slog.Info("slog.Info: that is ignored as it should")
slog.Warn("slog.Warn: that is logged as it should", "info.enabled", slog.Default().Enabled(slog.LevelInfo))
log.Print("log.Print: did not expect to see that in logs")

slog.Default().Handler().Handle(
  slog.NewRecord(
    time.Now(),
    slog.LevelInfo,
    "call.Handle: I guess thats ok if that is printed always",
    0, 
    nil,
))

// It is used to link the default log.Logger to the default slog.Logger.
func (w *handlerWriter) Write(buf []byte) (int, error) {
  ...
  r := NewRecord(time.Now(), LevelInfo, string(buf), depth, nil)
  return origLen, w.h.Handle(r)
}

func (w *handlerWriter) Write(buf []byte) (int, error) {
  if !w.h.Enabled(LevelInfo) {
    return 0, nil
  }
  ...
}