code: func NewWriterLogger(conf *WriterConfig, out io.Writer) (Logger, error) {
  	l := &writerLogger{}
  
  	base, err := NewLoggerBase(conf.BaseConfig, l.log)
  	if err != nil {
  		return nil, err
  	}
  
  	flags := log.LstdFlags
  	if conf.UTC {
  		flags |= log.LUTC
  	}
  
  	l.logger = log.New(out, conf.Prefix, flags)
  	l.LoggerBase = base
  
  	return l, nil
  }
docs: // NewWriterLogger creates a new io.Writer based logger.