code: func (l *coreLogger) Close() {
  	if !l.open {
  		return
  	}
  	l.open = false
  	// use a nil entry to signal the close of logger
  	l.entries <- nil
  	for _, target := range l.Targets {
  		target.Close()
  	}
  }
docs: // Close closes the logger and the targets.
  // Existing messages will be processed before the targets are closed.
  // New incoming messages will be discarded after calling this method.