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: tokens.go
    path of file: ./repos/magma/orc8r/cloud/go/services/certifier
    
    the code of the file until where you have to start completion: package certifier

import (
	"crypto/rand"
	"errors"
	"fmt"
	"hash/crc32"
	"strings"

	"github.com/jxskiss/base62"
)

type TokenType string

const (
	// Personal Orc8r personal token type
	Personal TokenType = "op"
)

// Length of checks
    
func validateTokenChecksum(token string) error {
	bytes, err := base62.StdEncoding.DecodeString(token)
	if err != nil {
		return err
	}
	bytesLen := len(bytes)
	if bytesLen < checksumLen {
		return errors.New("token not long enough")
	}
	claimedChecksum := btoi32(bytes[bytesLen-checksumLen:])
	calculatedChecksum := crc32.ChecksumIEEE(bytes[:bytesLen-checksumLen])
	if claimedChecksum != calculatedChecksum {
		return errors.New("invalid token checksum")
	}
	return nil
}