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: Err.go
    path of file: ./repos/scan4all/lib/Smuggling
    
    the code of the file until where you have to start completion: package Smuggling

import (
	"log"
	"strings"
)

// \u0000
var ErrPayload = []string{`
POST %s HTTP/1.1
Host: %s%s
Connection: Keep-Alive
Content-Length: 6
Content-Length: 5

12345GPOST / HTTP/1.1
Host: loca
    
func (r *Err) CheckResponse(body string, payload string) bool {
	//log.Println(body)
	if payload == ErrPayload[1] {
		return -1 < strings.Index(body, "400 Bad Request") && -1 < strings.Index(body, "200 OK")
	} else if payload == ErrPayload[2] || payload == ErrPayload[3] { // 要不成功访问到目标，要不得到404
		return -1 < strings.Index(body, "<defaultValue>") || (-1 < strings.Index(body, "400 Bad Request") && -1 < strings.Index(body, "HTTP/1.1 404 Not Found"))
	} else if "" != body && (-1 < strings.Index("Unrecognized method GPOST", body)) {
		log.Println("Unrecognized method GPOST")
		return true
	}
	return false
}