public async Task <int> SellBallotAsync(SaleInfo saleInfo)
{
Draw draw = _drawRepository.Get(saleInfo.DrawNumber);
Customer customer = _customerRepository.Get(saleInfo.CustomerNumber);
Ballot soldBallot = await _lottery.SellBallotAsync(draw, saleInfo.LastNumber);
customer.AddBallot(soldBallot);
_ballotRepository.Update(soldBallot, soldBallot.Id);
_customerRepository.Update(customer, customer.Number);
return(soldBallot.Number);
}