code: def get_serializable_dict(self):
          
          tmp = self.get_dict()
          tmp['date_download'] = str(tmp['date_download'])
          tmp['date_modify'] = str(tmp['date_modify'])
          tmp['date_publish'] = str(tmp['date_publish'])
          return tmp
docs: Get a serializable dict of the instance of this class.
          :return: