class Parent
    {
        public int MyProperty { get; set; }
        public void GetData()
        {
            Console.WriteLine("parent");
        }
    }



Parent[] p = new Parent[3]
    {
        new Parent(){MyProperty=90},
        new Parent(){MyProperty=50},
        new Parent(){MyProperty=100}
    };


foreach (var item in p)
    {
        Parent it = item;
        Console.WriteLine(it.MyProperty);
    }

public abstract class Array : ICloneable, IList, ICollection,
    IEnumerable, IStructuralComparable, IStructuralEquatable

public interface ICollection<T> : IEnumerable<T>, IEnumerable

public class Foo<T>
{
    public Foo(T value)
    {
        Value = value;
    }

    public T Value { get; }

    public FooEnumerator<T> GetEnumerator()
    {
        return new FooEnumerator<T>(Value);
    }
}

public class FooEnumerator<T>
{
    private bool _hasValue = true;
    private readonly T _value;

    public FooEnumerator(T value)
    {
        _value = value;
    }

    public bool MoveNext()
    {
        if (_hasValue)
        {
            Current = _value;
            return true;
        }
        else
        {
            _hasValue = false;
            return _hasValue;
        }
    }

    public T Current { get; private set; }
}

public class Test
{
    public static void Run()
    {
        foreach (var x in new Foo<int>(1))
        {
            Console.WriteLine(x);
        }
    }
}

public class Foo<T>
{
    public Foo(T value)
    {
        Value = value;
    }

    public T Value { get; }

    public Foo<U> Select<U>(Func<T, U> f)
    {
        return new Foo<U>(f(Value));
    }

    public Foo<U> SelectMany<U>(Func<T, Foo<U>> f)
    {
        return f(Value);
    }

    public Foo<V> SelectMany<U, V>(Func<T, Foo<U>> f, Func<T, U, V> g)
    {
        return new Foo<V>(g(Value, f(Value).Value));
    }
}

public class Test
{
    public static void Run()
    {
        var result =
            from x in new Foo<int>(5)
            from y in new Foo<int>(9)
            select (x + y).ToString();

        // result is now a Foo<string> containing the value "14"
    }
}