title: Using msgpack-python with nested namedtuples
body: <p>My data structure is like this:</p>
  
  <pre><code>user = UserTuple(
      name=u'Anakin', surname=u'Skywalker', birthdate=datetime.date(1981, 7, 25),
      profile=ProfileTuple(avatar=u'http://localhost/profile.jpg')
  )
  </code></pre>
  
  <p>And I want to pack this data with msgpack-python module. But msgpack converts namedtuples to lists. It can be possible pack data like this with msgpack and preserve namedtuples, just like pickle/cpickle?</p>