code: func IsSpecialNetwork(ip net.IP) bool {
  	if ip.IsMulticast() {
  		return true
  	}
  	if v4 := ip.To4(); v4 != nil {
  		return special4.Contains(v4)
  	}
  	return special6.Contains(ip)
  }
docs: // IsSpecialNetwork reports whether an IP is located in a special-use network range
  // This includes broadcast, multicast and documentation addresses.