new_contents: import gdal
  from spacegrid import SpatialGrid
  
  class GeotiffGrid(SpatialGrid):
      def __init__(self, filepath):
          ds = gdal.Open(filepath)
          x0_corner, sizex, zero1, y0_corner, zero2, sizey = ds.GetGeoTransform()
          band = ds.GetRasterBand(1)
          array = band.ReadAsArray()
  
          self.array = array
          super(BinaryGrid, self).__init__(x0_corner, y0_corner, sizex, sizey, array.shape[2], array.shape[1])
  
      def getll_raw(self, latitude, longitude):
          return self.array[self.rowcol(latitude, longitude)]
  
subject: add way to read geotiffs