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: meta.go
    path of file: ./repos/kubeedge/vendor/github.com/BurntSushi/toml
    
    the code of the file until where you have to start completion: package toml

import (
	"strings"
)

// MetaData allows access to meta information about TOML data that's not
// accessible otherwise.
//
// It allows checking if a key is defined in the TOML data, whether any keys
// were undecoded, and the TOML type of a key.
type MetaData struct {
	context Key // Used only during decoding.

	keyInfo map[str
    
func (md *MetaData) IsDefined(key ...string) bool {
	if len(key) == 0 {
		return false
	}

	var (
		hash      map[string]interface{}
		ok        bool
		hashOrVal interface{} = md.mapping
	)
	for _, k := range key {
		if hash, ok = hashOrVal.(map[string]interface{}); !ok {
			return false
		}
		if hashOrVal, ok = hash[k]; !ok {
			return false
		}
	}
	return true
}