title: protobuf with inheritance?
body: <p>Is it possible to use <a href="http://code.google.com/p/protobuf/" rel="noreferrer">protobuf</a> with classes who inherit?</p>
  
  <p>I want to do something like this</p>
  
  <pre><code>class Expr;
  class AddExpr : Expr;
  class CallFunc: Expr;
  
  class FunctionBody{
      repeatable Expr expr;
  }
  </code></pre>