code: func SolicitedNodeAddr(addr tcpip.Address) tcpip.Address {
  	const solicitedNodeMulticastPrefix = "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xff"
  	return solicitedNodeMulticastPrefix + addr[len(addr)-3:]
  }
docs: // SolicitedNodeAddr computes the solicited-node multicast address. This is
  // used for NDP. Described in RFC 4291. The argument must be a full-length IPv6
  // address.