using System.Collections.Generic;

interface IA
{
}

interface IB : IA
{
}

static class E
{
	internal static void ToReadOnly<T>(this IEnumerable<T> source)
	{
	}
	
	internal static void To (this IA i)
	{
	}
}

class C
{
	public static void Main ()
	{
	}
	
	public static void Test (IEnumerable<bool> bindings)
	{
		bindings.ToReadOnly();
		
		IB ib = null;
		ib.To ();
	}
}