I'd like to point out that the extension method feature of C# is one big reason why I like this whole story much better than the Streams API in Java. There are often methods I wish were part of the IEnumerable interface, and with extension methods, I can add them myself! (if they are not already provided in, say, MoreLinq [1]). Very convenient, and a big boost in productivity.
https://github.com/morelinq/MoreLINQ