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: idna10.0.0.go
    path of file: ./repos/kubeedge/vendor/golang.org/x/net/idna
    
    the code of the file until where you have to start completion: // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.10
// +build go1.10

// Package idna implements IDNA2008 using the compatibility processing
// defined by UTS (Unicode Technical Standard) #46, which defines a standard to
// deal with the transition from IDNA2003.
//
// IDNA2008 (Internationalized Domain Names for Applications), is defined in RFC
// 5890, RFC 5891, RFC 5892, RFC 5893 and RFC 5894.
// UTS #46 is defined in https://www.unicode.org/reports/tr46.
// See https://unicode.org/cldr/utility/idna.jsp for a visualization of the
// differences between these two standards.
package idna // import "go
    
func (p *Profile) validateLabel(s string) (err error) {
	if s == "" {
		if p.verifyDNSLength {
			return &labelError{s, "A4"}
		}
		return nil
	}
	if p.checkHyphens {
		if len(s) > 4 && s[2] == '-' && s[3] == '-' {
			return &labelError{s, "V2"}
		}
		if s[0] == '-' || s[len(s)-1] == '-' {
			return &labelError{s, "V3"}
		}
	}
	if !p.checkJoiners {
		return nil
	}
	trie := p.trie // p.checkJoiners is only set if trie is set.
	// TODO: merge the use of this in the trie.
	v, sz := trie.lookupString(s)
	x := info(v)
	if x.isModifier() {
		return &labelError{s, "V5"}
	}
	// Quickly return in the absence of zero-width (non) joiners.
	if strings.Index(s, zwj) == -1 && strings.Index(s, zwnj) == -1 {
		return nil
	}
	st := stateStart
	for i := 0; ; {
		jt := x.joinType()
		if s[i:i+sz] == zwj {
			jt = joinZWJ
		} else if s[i:i+sz] == zwnj {
			jt = joinZWNJ
		}
		st = joinStates[st][jt]
		if x.isViramaModifier() {
			st = joinStates[st][joinVirama]
		}
		if i += sz; i == len(s) {
			break
		}
		v, sz = trie.lookupString(s[i:])
		x = info(v)
	}
	if st == stateFAIL || st == stateAfter {
		return &labelError{s, "C"}
	}
	return nil
}