public async Task HandleAsync(CreatePhoneBookCommand command)
{
var phoneBook = await _phoneBookRepository.GetPhoneBookByNameAsync(command.Name);
if (phoneBook != null)
{
throw new ValidateException("Phone book already exists");
}
await _phoneBookRepository.AddAsync(new Entities.PhoneBookAggregateRoot(command.Name));
await _phoneBookRepository.SaveAsync();
}