using System;

using System.Collections.Generic;

using System.Drawing;

using System.Linq;

​

public class Hat

{

    public Color Color { get; set; }

    public bool IsGreen() => Color == Color.Green;

}

​

public class Program

{

    public static void Main()

    {

        List<Hat> hats = [];

        Console.WriteLine($"All hats are green: {hats.All(h => h.IsGreen())}");

    }

}