title: Allow a mock class to inherit from a final class
body: <p>We may declare a final/sealed non-inheritable class using the new C++ keyword <code>final</code>. </p>
  
  <pre><code>class Generator final
  {
  
  };
  </code></pre>
  
  <p>This class may inherit from other, may or may not have virtual (inherited or not). But, how to make it <code>final</code>, yet allow one class to inherit from it? </p>
  
  <p>We mostly need to derive a mock class from real class (with or without late-binding, hence <code>virtual</code> isn't important). How to make it work:</p>
  
  <pre><code>class MockGenerator : Generator{};
  </code></pre>
  
  <p>But disallow any other inheritance?</p>