code: func (c *KCPConfig) Init() {
  	switch c.Mode {
  	case "normal":
  		c.NoDelay, c.Interval, c.Resend, c.NoCongestion = 0, 40, 2, 1
  	case "fast":
  		c.NoDelay, c.Interval, c.Resend, c.NoCongestion = 0, 30, 2, 1
  	case "fast2":
  		c.NoDelay, c.Interval, c.Resend, c.NoCongestion = 1, 20, 2, 1
  	case "fast3":
  		c.NoDelay, c.Interval, c.Resend, c.NoCongestion = 1, 10, 2, 1
  	}
  }
docs: // Init initializes the KCP config.