C# Online Compiler | .NET Fiddle

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace MaybeProp
{
	public class Program
	{
		public static void Main(string[] args)
		{
			int[] ids = new[] { 1, 2, 3, 4, 5 };

			var storage = new Storage();

			foreach (var id in ids)
			{
				Console.WriteLine("{0}: {1}", storage.GetStorageName(id), storage.GetContent(id));
			}
			Console.WriteLine();

			var someStorage = new NotSoReliableStorage();

			foreach (var id in ids)
			{
				try
				{
					Console.WriteLine("{0}: {1}", someStorage.GetStorageName(id), someStorage.GetContent(id));
				}
				catch
				{
					Console.WriteLine("{0}: NO CONTENT", someStorage.GetStorageName(id));
				}
			}
			Console.WriteLine();

			var betterStorage = new BetterNotSoReliableStorage();

			foreach (var id in ids)
			{
				string message = "";

				if (betterStorage.TryGetContent(id, out message))
					Console.WriteLine("{0}: {1}", betterStorage.GetStorageName(id), message);
				else
					Console.WriteLine("{0}: NO CONTENT", betterStorage.GetStorageName(id));
			}
			Console.WriteLine();

			var maybeStorage = new MaybeStorage();

			foreach (var id in ids)
			{
				Console.WriteLine("{0}: {1}",
									maybeStorage.GetStorageName(id),
									maybeStorage.GetContent(id)
										.DefaultIfEmpty(string.Format("NO CONTENT"))
									.Single());
			}

		}
	}

	public class Storage
	{
		public string GetStorageName(int id)
		{
			return Path.Combine(@"C:\", id + ".txt");
		}
		public string GetContent(int id)
		{
			return string.Concat(Enumerable.Repeat("hello ", id));
		}
	}

	public class NotSoReliableStorage
	{
		public string GetStorageName(int id)
		{
			return Path.Combine(@"C:\", id + ".txt");
		}
		public string GetContent(int id)
		{
			if (id % 2 == 0)
				throw new ArgumentException("Cannot find it");

			return string.Concat(Enumerable.Repeat("hello ", id));
		}
	}

	public class BetterNotSoReliableStorage
	{
		public string GetStorageName(int id)
		{
			return Path.Combine(@"C:\", id + ".txt");
		}
		public bool TryGetContent(int id, out string content)
		{
			if (id % 2 == 0)
			{
				content = null;
				return false;
			}

			content = string.Concat(Enumerable.Repeat("hello ", id));
			return true;
		}
	}

	public class MaybeStorage
	{
		public string GetStorageName(int id)
		{
			return Path.Combine(@"C:\", id + ".txt");
		}
		public Maybe<string> GetContent(int id)
		{
			if (id % 2 == 0)
				return new Maybe<string>();

			return new Maybe<string>(string.Concat(Enumerable.Repeat("hello ", id)));
		}
	}

	public class Maybe<T> : IEnumerable<T>
	{
		private readonly IEnumerable<T> values;

		public Maybe()
		{
			this.values = new T[0];
		}

		public Maybe(T value)
		{
			this.values = new[] { value };
		}
		public IEnumerator<T> GetEnumerator()
		{
			return this.values.GetEnumerator();
		}

		IEnumerator IEnumerable.GetEnumerator()
		{
			return this.GetEnumerator();
		}
	}
}

 
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
​
namespace MaybeProp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int[] ids = new[] { 1, 2, 3, 4, 5 };
​
            var storage = new Storage();
​
            foreach (var id in ids)
            {
                Console.WriteLine("{0}: {1}", storage.GetStorageName(id), storage.GetContent(id));
            }
            Console.WriteLine();
​
            var someStorage = new NotSoReliableStorage();
​

Cached Result

4 / 2: 2
100 / 3: 33
100 / 100: 1
100 / 101: 0
50 / 25: 2
127 / 2: 63