examples/advanced/rect/shapes.py
import copy

class Rect(object):
    def __init__(self, w, h):
        self.width  = w
        self.height = h


    def __str__(self):
        return 'Rect[{}, {}]'.format(self.width, self.height)

    def __mul__(self, other):
        o = int(other)
        new = copy.deepcopy(self)
        new.height *= o
        return new

examples/advanced/rect/rect.py
import shapes

r = shapes.Rect(10, 20)
print(r)
print(r * 3)
print(r)

print(4 * r) 
examples/advanced/rect/rect.out
Rect[10, 20]
Rect[10, 60]
Rect[10, 20]
Traceback (most recent call last):
  File "rect.py", line 8, in <module>
    print(4 * r) 
TypeError: unsupported operand type(s) for *: 'int' and 'Rect'

In order to make the multiplication work in the other direction, one needs to implement the __rmul__ method.