Define an Extension Method for IEnumerable which returns IEnumerable?

Question

How do I define an Extension Method for IEnumerable which returns IEnumerable? The goal is to make the Extension Method available for

Answer 1

This post may help you to get started:How do you write a C# Extension Method for a Generically Typed Class. I'm not sure if it is exactly what you are looking for but it might get you started.