title: Enumerable.Empty<T>() equivalent for IQueryable
body: <p>When a method returns <code>IEnumerable&lt;T&gt;</code> and I do not have anything to return, we can use <code>Enumerable.Empty&lt;T&gt;()</code>.</p>
  
  <p>Is there an equivalent to the above for a method returning <code>IQueryable&lt;T&gt;</code></p>