You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ipbits.go
    path of file: ./repos/moby/libnetwork/ipbits
    
    the code of the file until where you have to start completion: // Package ipbits contains utilities for manipulating [netip.Addr] values as
// numbers or
    
func Add(ip netip.Addr, x uint64, shift uint) netip.Addr {
	if ip.Is4() {
		a := ip.As4()
		addr := binary.BigEndian.Uint32(a[:])
		addr += uint32(x) << shift
		binary.BigEndian.PutUint32(a[:], addr)
		return netip.AddrFrom4(a)
	} else {
		a := ip.As16()
		addr := uint128From16(a)
		addr = addr.add(uint128From(x).lsh(shift))
		addr.fill16(&a)
		return netip.AddrFrom16(a)
	}
}