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: property.go
    path of file: ./repos/cellnet/peer
    
    the code of the file until where you have to start completion: package peer

import (
	"reflect"
	"sync"
)

type ctx struct {
	key   interface{}
	value interface{}
}

// 上下文记录，绑定用户自定义数据
type CoreContextSet struct {
    
func (self *CoreContextSet) SetContext(key, v interface{}) {

	self.ctxesGuard.Lock()
	defer self.ctxesGuard.Unlock()

	for i, t := range self.ctxes {
		if t.key == key {
			self.ctxes[i] = ctx{key, v}
			return
		}
	}

	self.ctxes = append(self.ctxes, ctx{key, v})
}