code: def scale_xy(self, x=0, y=None):
          
          self.root.set("transform", "%s scale(%f %f)" %
                        (self.root.get("transform") or '',
                         x, y if y is not None else ''))
docs: Scale element separately across the two axes x and y.
              If y is not provided, it is assumed equal to x (according to the
              W3 specification).
  
          Parameters
          ----------
          x : float
              x-axis scaling factor. To scale down x < 1, scale up x > 1.
          y : (optional) float
              y-axis scaling factor. To scale down y < 1, scale up y > 1.