code: func (logger *Logger) WithFields(fields logging.Fields) logging.LogWithLevel {
  	return logger.withFields(fields, 1)
  }
docs: // WithFields creates an entry from the standard logger and adds multiple
  // fields to it. This is simply a helper for `WithField`, invoking it
  // once for each field.
  //
  // Note that it doesn't log until you call Debug, Print, Info, Warn, Fatal
  // or Panic on the LogMsg it returns.