Create or update a playlist.

def save(self):
        """
        Create or update a playlist.
        """
        d = self._to_dict()
        if len(d.get('videoIds', [])) > 0:
            if not self.id:
                self.id = self.connection.post('create_playlist', playlist=d)
            else:
                data = self.connection.post('update_playlist', playlist=d)
                if data:
                    self._load(data)