/// <summary>
/// Save this storage to the repo
/// </summary>
/// <param name="repo">The repo to store</param>
/// <exception cref="ArgumentNullException">Throws when repo is null</exception>
public void SaveTo(IBookListStorage repo)
{
if (repo == null)
{
throw new ArgumentNullException($"{nameof(repo)} must be not null");
}
repo.WriteBooks(books);
}