code: def get_fn(elev, name=None):
      
      gcs = elev.grid_coordinates
      coords = [gcs.LLC.lat, gcs.LLC.lon, gcs.URC.lat, gcs.URC.lon]
      return get_fn_from_coords(coords, name)
docs: Determines the standard filename for a given GeoTIFF Layer.
  
      Parameters
      -----------
      elev : GdalReader.raster_layer
          A raster layer from the GdalReader object.
      name : str (optional)
          An optional suffix to the filename.
      Returns
      -------
      fn : str
          The standard <filename>_<name>.tif with suffix (if supplied)