code: def read(self, output_tile, **kwargs):
          
          try:
              return ma.masked_values(
                  read_raster_no_crs(
                      self.get_path(output_tile), indexes=(4 if self.old_band_num else 2)
                  ),
                  0
              )
          except FileNotFoundError:
              return self.empty(output_tile)
docs: Read existing process output.
  
          Parameters
          ----------
          output_tile : ``BufferedTile``
              must be member of output ``TilePyramid``
  
          Returns
          -------
          process output : ``BufferedTile`` with appended data