Get all the word boxes of this page.

def __get_boxes(self):
        """
        Get all the word boxes of this page.
        """
        boxfile = self.__box_path

        try:
            box_builder = pyocr.builders.LineBoxBuilder()
            with self.fs.open(boxfile, 'r') as file_desc:
                boxes = box_builder.read_file(file_desc)
            if boxes != []:
                return boxes
            # fallback: old format: word boxes
            # shouldn't be used anymore ...
            box_builder = pyocr.builders.WordBoxBuilder()
            with self.fs.open(boxfile, 'r') as file_desc:
                boxes = box_builder.read_file(file_desc)
            if len(boxes) <= 0:
                return []
            logger.warning("WARNING: Doc %s uses old box format" %
                           (str(self.doc)))
            return [pyocr.builders.LineBox(boxes, boxes[0].position)]
        except IOError as exc:
            logger.error("Unable to get boxes for '%s': %s"
                         % (self.doc.docid, exc))
            return []