title: UUID send to client with str(value) but ib server when receive back badly formed hexadecimal string
body: <p>I ma using in SQLAlchemy uuid4 for one column and I got value like <code>16d11d6abdaf4fe9905a56e0be8d15d1</code>
  I need to send this id to client using json format and in future to receive from client id and make query over database.
  I am sending like</p>
  
  <pre><code>result = {'id': str(id)}
  #this is from Tornado handler
  self.write(simplejson.dumps(result))
  </code></pre>
  
  <p>when I send from user json with id which I received, on server I extract like </p>
  
  <pre><code>data = tornado.escape.json_decode(self.request.body)
  id = data.get('id', None)
  #also tornado handler when I receive id from client
  #I also have tried like uuid.UUID(bytes=id.bytes) but also get error
  </code></pre>
  
  <p>I always get error like badly formed hexadecimal string. How to send to client and from client to server uuid in json ? </p>