code: func FlushPeriod(p time.Duration) Option {
  	return Option(func(c *config) {
  		c.Conn.FlushPeriod = p
  	})
  }
docs: // FlushPeriod sets how often the Client's buffer is flushed. If p is 0, the
  // goroutine that periodically flush the buffer is not lauched and the buffer
  // is only flushed when it is full.
  //
  // By default, the flush period is 100 ms.  This option is ignored in
  // Client.Clone().