title: Define an Extension Method for IEnumerable<T> which returns IEnumerable<T>?
body: <p>How do I define an Extension Method for <code>IEnumerable&lt;T&gt;</code> which returns <code>IEnumerable&lt;T&gt;</code>?
  The goal is to make the Extension Method available for all <code>IEnumerable</code> and <code>IEnumerable&lt;T&gt;</code> where <code>T</code> can be an anonymous type.</p>