p.s. Here is a test to see if your students understand about binding, or if they are walking around with it confused with equality.

...

...

class Animal: ... def __init__(eyecolour, sound, action): ... self.eyecolour = eyecolour ... self.sound = sound ... self.action = action ... cat = Animal('green', 'miaux', 'pounce') dog = Animal('brown', 'woof', 'wag') vlerb = Animal('green', 'miaux', 'pounce')

Now go ask them if what they think vlerb == cat will print. This is an easier place to clear up the misunderstanding than the first time they start passing mutable objects as defaults to a function or a method, which is where my classes in the past have tended to blow up with this sort of misunderstanding. Laura