 got:</p>  <ul>   <li>Cast and OfType </li>    <li>ElementAt and ElementAtOrDefault </li>    <li>SequenceEqual </li>    <li>Zip (from .NET 4) </li>    <li>Contains </li> </ul>  <p>However, that doesn&#39;t include AsEnumerable and AsQueryable. I&#39;m unsure at the moment what I&#39;m doing with those... AsEnumerable is trivial, and probably worth doing... AsQueryable could prove interesting in terms of testing, as it requires expression trees (which are in System.Core; a library I&#39;m not referencing fro