code: def extent(self):
          
  
          return (
              self.ixmin - 0.5,
              self.ixmax - 0.5,
              self.iymin - 0.5,
              self.iymax - 0.5,
          )
docs: The extent of the mask, defined as the ``(xmin, xmax, ymin,
          ymax)`` bounding box from the bottom-left corner of the
          lower-left pixel to the upper-right corner of the upper-right
          pixel.
  
          The upper edges here are the actual pixel positions of the
          edges, i.e. they are not "exclusive" indices used for python
          indexing.  This is useful for plotting the bounding box using
          Matplotlib.