IGrouping不包含求和的定义

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

        var groupedNumbers = numbers.GroupBy(n => n % 2 == 0 ? "Even" : "Odd");

        foreach (var group in groupedNumbers)
        {
            Console.WriteLine("Key: " + group.Key);
            Console.WriteLine("Sum: " + group.Sum());
            Console.WriteLine("Numbers: " + string.Join(", ", group));
            Console.WriteLine();
        }
    }
}