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: map_claims.go
    path of file: ./repos/kubernetes/vendor/github.com/golang-jwt/jwt/v4
    
    the code of the file until where you have to start completion: package jwt

import (
	"encoding/json"
	"errors"
	"time"
	// "fmt
    
func (m MapClaims) Valid() error {
	vErr := new(ValidationError)
	now := TimeFunc().Unix()

	if !m.VerifyExpiresAt(now, false) {
		// TODO(oxisto): this should be replaced with ErrTokenExpired
		vErr.Inner = errors.New("Token is expired")
		vErr.Errors |= ValidationErrorExpired
	}

	if !m.VerifyIssuedAt(now, false) {
		// TODO(oxisto): this should be replaced with ErrTokenUsedBeforeIssued
		vErr.Inner = errors.New("Token used before issued")
		vErr.Errors |= ValidationErrorIssuedAt
	}

	if !m.VerifyNotBefore(now, false) {
		// TODO(oxisto): this should be replaced with ErrTokenNotValidYet
		vErr.Inner = errors.New("Token is not valid yet")
		vErr.Errors |= ValidationErrorNotValidYet
	}

	if vErr.valid() {
		return nil
	}

	return vErr
}