docs: def aggregate(raster, ndv, block_size):
      '''
      Aggregate raster to smaller resolution, by adding cells.
      Usage:
              aggregate(raster, ndv, block_size)
  
      where:
              raster is a Numpy array created by importing the raster (e.g. geotiff)
  
              ndv is the NoData Value for the raster (can be read using the get_geo_info function)
  
              block_size is a duple of factors by which the raster will be shrinked
  
      Example:
              raster = HMISea.tif
  
              ndv, xsize, ysize, geot, projection, datatype = get_geo_info(raster)
  
              costs = load_tiff(raster)
  
              costs2=aggregate(costs, ndv, (10,10))
      '''
      raster2 = block_reduce(raster, block_size, func=np.ma.sum)
      return raster2