public void ChangeQuantity(string itemId, int newQuantity) {  
    if (newQuantity < 0) throw new ArgumentException("Количество не может быть отрицательным");  
    var item = items.FirstOrDefault(i => i.Id == itemId);  
    if (item != null) {  
        item.Quantity = newQuantity;  
        RecalculateTotal();  
    }  
}  

var nowUtc = DateTimeOffset.UtcNow;
var moscow = TimeZoneInfo.FindSystemTimeZoneById("Europe/Moscow");
var nowMoscow = TimeZoneInfo.ConvertTime(nowUtc, moscow);

Console.WriteLine(nowUtc);
Console.WriteLine(nowMoscow);

var vacation = new DateOnly(2026, 1, 10);
var standup = new TimeOnly(10, 30);

Console.WriteLine(vacation);
Console.WriteLine(standup);

var year = new Year(2026);
year.Wishes = new[] { "чистый код", "нулевой техдолг", "стабильный прод" };

while (year.InProgress)
{
    await you.Ship(Features.Amazing);
    await you.Avoid(Bugs.Critical);
    you.Happiness++;
}

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

static async IAsyncEnumerable<int> GenerateSequenceAsync(int count, [EnumeratorCancellation] CancellationToken token = default)
{
    for (int i = 0; i < count; i++)
    {
        // Симулируем асинхронную задержку
        await Task.Delay(100, token);
        yield return i;
    }
}

static async Task ConsumeAsync()
{
    await foreach (var item in GenerateSequenceAsync(5))
    {
        Console.WriteLine($"Получено значение: {item}");
    }
}

using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(1));
try
{
    await foreach (var item in GenerateSequenceAsync(10, cts.Token).WithCancellation(cts.Token))
    {
        Console.WriteLine(item);
    }
}
catch (OperationCanceledException)
{
    Console.WriteLine("Операция была отменена.");
}