docs: def affine(self, pixelbuffer=0):
          """
          Return an Affine object of tile.
  
          - pixelbuffer: tile buffer in pixels
          """
          return Affine(
              self.pixel_x_size,
              0,
              self.bounds(pixelbuffer).left,
              0,
              -self.pixel_y_size,
              self.bounds(pixelbuffer).top
          )