code: def _slice_data(self, source_area, slices, dataset):
          
          slice_x, slice_y = slices
          dataset = dataset.isel(x=slice_x, y=slice_y)
          assert ('x', source_area.x_size) in dataset.sizes.items()
          assert ('y', source_area.y_size) in dataset.sizes.items()
          dataset.attrs['area'] = source_area
  
          return dataset
docs: Slice the data to reduce it.