export function validateISBN13(isbn: string): boolean {
  let sum = 0

  for (let i = 0; i < 12; i++) {
    const digit = Number(isbn[i])

    sum += i % 2 === 0 ? digit : digit * 3
  }

  const checkDigit = (10 - (sum % 10)) % 10

  return checkDigit === Number(isbn[12]);
}