title: AnyIterator and boost iterator facade
body: <p>Is it possible to implement an any iterator with boost iterator facade? 
  I don't want to define implementation details in my baseclass</p>
  
  <pre><code>class Base
  {
  public:
  typedef std::vector&lt;int&gt;::iterator iterator;//implementation detail
  ...
  virtual iterator begin()=0;
  virtual iterator end()=0;
  };
  </code></pre>
  
  <p>or do i have to write one completely from scratch;</p>