ListUtils.cs

using System;
using System.Collections;
using System.Collections.Generic;

public static class ListUtils
{
    public static void Shuffle (this IList list)  
    {  
        Random rng = new Random();  

        int n = list.Count;  

        while (n > 1)
        {  
            n--;  
            int k = rng.Next(n + 1);  
            var value = list[k];  
            list[k] = list[n];  
            list[n] = value;  
        }  
    }
    
    public static T PopFirst<T>(this List<T> list)
    {
        T poppedValue = list[0];
        list.RemoveAt(0);
        return poppedValue;
    }

    public static T PopLast<T> (this List<T> list)
    {
        T poppedValue = list[list.Count - 1];
        list.RemoveAt(list.Count - 1);
        return poppedValue;
    }
    
    public static T PopNth<T> (this List<T> list, int n)
    {
        T poppedValue = list[n];
        list.RemoveAt(n);
        return poppedValue;
    }
    
    public static T GetRandom<T> (this List<T> list)
    {
        Random rng = new Random();
        return list[rng.Next() % list.Count];
    }
}