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

public static class SimpleEnumerable
{
    public static IEnumerable<TSource> SimpleWhere<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
    {
    	foreach (TSource element in source)
    	{
    		if (predicate(element))
    		{
    			yield return element;
    		}
    	}
    }
}

public class MyClass
{
    private string _att01;
    private string _att02;
    private string _att03;
    public int instanceNum;

    public string att01
    {
        get
        {
            Console.WriteLine("att01 of instance {0}", instanceNum);
            return _att01;
        }
        set
        {
            _att01 = value;
        }
    }

    public string att02
    {
        get
        {
            Console.WriteLine("att02 of instance {0}", instanceNum);
            return _att02;
        }
        set
        {
            _att02 = value;
        }
    }
    
    public string att03
    {
        get
        {
            Console.WriteLine("att03 of instance {0}", instanceNum);
            return _att03;
        }
        set
        {
            _att03 = value;
        }
    }
}

public class Test
{
	public static void Main()
	{
	    var coll = new[] 
	    {
	        new MyClass { instanceNum = 0, att01 = "A", att02 = "B", att03 = "C" },
	        new MyClass { instanceNum = 1, att01 = "X", att02 = "B", att03 = "C" },
	        new MyClass { instanceNum = 2, att01 = "X", att02 = "Y", att03 = "C" },
	        new MyClass { instanceNum = 3, att01 = "X", att02 = "Y", att03 = "Z" },
	    };
	
	    Console.WriteLine("Method 1");
	    var list1 = coll
	        .Where(x => x.att01 == "X")
	        .Where(x => x.att02 == "Y")
	        .Where(x => x.att03 == "Z")
	        .SingleOrDefault();
	
	    Console.WriteLine();
	    Console.WriteLine("Method 2");
	    var list2 = coll
	        .Where(x => x.att01 == "X" && x.att02 == "Y" && x.att03 == "Z")
	        .SingleOrDefault();

	    Console.WriteLine("Method 3");
	    var list3 = coll
	        .SimpleWhere(x => x.att01 == "X")
	        .SimpleWhere(x => x.att02 == "Y")
	        .SimpleWhere(x => x.att03 == "Z")
	        .SingleOrDefault();
	
	}
}