docs: def _process(self, segments):
          """sort segments in read order - left to right, up to down"""
          # sort_f= lambda r: max_line_width*(r[1]/max_line_height)+r[0]
          # segments= sorted(segments, key=sort_f)
          # segments= segments_to_numpy( segments )
          # return segments
          mlh, mlw = self.max_line_height, self.max_line_width
          s = segments.astype(numpy.uint32)  # prevent overflows
          order = mlw * (s[:, 1] // mlh) + s[:, 0]
          sort_order = numpy.argsort(order)
          return segments[sort_order]