docs: def get(self):
          """
          :return: response stats dict
          """
          stats = {}
          if self.start_date is not None:
              stats["start_date"] = self.start_date
          if self.end_date is not None:
              stats["end_date"] = self.end_date
          if self.aggregated_by is not None:
              stats["aggregated_by"] = self.aggregated_by
          if self.sort_by_metric is not None:
              stats["sort_by_metric"] = self.sort_by_metric
          if self.sort_by_direction is not None:
              stats["sort_by_direction"] = self.sort_by_direction
          if self.limit is not None:
              stats["limit"] = self.limit
          if self.offset is not None:
              stats["offset"] = self.offset
          if self.categories is not None:
              stats['categories'] = [category.get() for category in
                                     self.categories]
          return stats