code: def transpose(self, method):
          
          if method not in (FLIP_LEFT_RIGHT, FLIP_TOP_BOTTOM):
              raise NotImplementedError(
                  "Only FLIP_LEFT_RIGHT and FLIP_TOP_BOTTOM implemented"
              )
  
          image_width, image_height = self.size
          xmin, ymin, xmax, ymax = self._split_into_xyxy()
          if method == FLIP_LEFT_RIGHT:
              TO_REMOVE = 1
              transposed_xmin = image_width - xmax - TO_REMOVE
              transposed_xmax = image_width - xmin - TO_REMOVE
              transposed_ymin = ymin
              transposed_ymax = ymax
          elif method == FLIP_TOP_BOTTOM:
              transposed_xmin = xmin
              transposed_xmax = xmax
              transposed_ymin = image_height - ymax
              transposed_ymax = image_height - ymin
  
          transposed_boxes = torch.cat(
              (transposed_xmin, transposed_ymin, transposed_xmax, transposed_ymax), dim=-1
          )
          bbox = BoxList(transposed_boxes, self.size, mode="xyxy")
          # bbox._copy_extra_fields(self)
          for k, v in self.extra_fields.items():
              if not isinstance(v, torch.Tensor):
                  v = v.transpose(method)
              bbox.add_field(k, v)
          return bbox.convert(self.mode)
docs: Transpose bounding box (flip or rotate in 90 degree steps)
          :param method: One of :py:attr:`PIL.Image.FLIP_LEFT_RIGHT`,
            :py:attr:`PIL.Image.FLIP_TOP_BOTTOM`, :py:attr:`PIL.Image.ROTATE_90`,
            :py:attr:`PIL.Image.ROTATE_180`, :py:attr:`PIL.Image.ROTATE_270`,
            :py:attr:`PIL.Image.TRANSPOSE` or :py:attr:`PIL.Image.TRANSVERSE`.