private async static Task <string> AddNewSubscriptionAndGetName(string mail, string number, int?diffPercent, int?diffPln)
{
using SqlConnection conn = ConnectionFactory.CreateConnection();
conn.Open();
Subscriber subscriber = DbUtilities.GetOrCreateSubscriber(conn, mail);
LegoSet set = await DbUtilities.GetOrCreateSet(conn, int.Parse(number));
Subscription subscription = CreateSubscription(subscriber, set, diffPercent, diffPln);
DbUtilities.CreateOrUpdateSubscriptionInDb(conn, subscription);
return(set.Name);
}