docs: def _to_dict(self):
          """
          Internal method that serializes object into a dictionary.
          """
          data = {
              'name': self.name,
              'referenceId': self.reference_id,
              'shortDescription': self.short_description,
              'playlistType': self.type,
              'id': self.id}
          if self.videos:
              for video in self.videos:
                  if video.id not in self.video_ids:
                      self.video_ids.append(video.id)
          if self.video_ids:
              data['videoIds'] = self.video_ids
          [data.pop(key) for key in data.keys() if data[key] == None]
          return data