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: xfrm_state.go
    path of file: ./repos/buildkit/vendor/github.com/vishvananda/netlink
    
    the code of the file until where you have to start completion: package netlink

import (
	"fmt"
	"net"
	"time"
)

// XfrmStateAlgo represents the algorithm to use for the ips
    
func (e EncapType) String() string {
	switch e {
	case XFRM_ENCAP_ESPINUDP_NONIKE:
		return "espinudp-non-ike"
	case XFRM_ENCAP_ESPINUDP:
		return "espinudp"
	}
	return "unknown"
}