code: func (kcp *KCP) NoDelay(nodelay, interval, resend, nc int) int {
  	if nodelay >= 0 {
  		kcp.nodelay = uint32(nodelay)
  		if nodelay != 0 {
  			kcp.rx_minrto = IKCP_RTO_NDL
  		} else {
  			kcp.rx_minrto = IKCP_RTO_MIN
  		}
  	}
  	if interval >= 0 {
  		if interval > 5000 {
  			interval = 5000
  		} else if interval < 10 {
  			interval = 10
  		}
  		kcp.interval = uint32(interval)
  	}
  	if resend >= 0 {
  		kcp.fastresend = int32(resend)
  	}
  	if nc >= 0 {
  		kcp.nocwnd = int32(nc)
  	}
  	return 0
  }
docs: // NoDelay options
  // fastest: ikcp_nodelay(kcp, 1, 20, 2, 1)
  // nodelay: 0:disable(default), 1:enable
  // interval: internal update timer interval in millisec, default is 100ms
  // resend: 0:disable fast resend(default), 1:enable fast resend
  // nc: 0:normal congestion control(default), 1:disable congestion control