code: def update(self, items):
          
          post_data = {}
          items_json = json.dumps(items, default=dthandler)
          post_data['data'] = items_json
  
          response = self.post_attribute("update", data=post_data)
  
          return response['ticket']
docs: Update a catalog object
  
          Args:
              items (list): A list of dicts describing update data and action codes (see api docs)
  
          Kwargs:
  
          Returns:
              A ticket id
  
          Example:
  
          >>> c = catalog.Catalog('my_songs', type='song')
          >>> items
          [{'action': 'update',
            'item': {'artist_name': 'dAn ThE aUtOmAtOr',
                     'disc_number': 1,
                     'genre': 'Instrumental',
                     'item_id': '38937DDF04BC7FC4',
                     'play_count': 5,
                     'release': 'Bombay the Hard Way: Guns, Cars & Sitars',
                     'song_name': 'Inspector Jay From Dehli',
                     'track_number': 9,
                     'url': 'file://localhost/Users/tylerw/Music/iTunes/iTunes%20Media/Music/Dan%20the%20Automator/Bombay%20the%20Hard%20Way_%20Guns,%20Cars%20&%20Sitars/09%20Inspector%20Jay%20From%20Dehli.m4a'}}]
          >>> ticket = c.update(items)
          >>> ticket
          u'7dcad583f2a38e6689d48a792b2e4c96'
          >>> c.status(ticket)
          {u'ticket_status': u'complete', u'update_info': []}
          >>>