how do i create such a thing?

[Lowell Kirsh]

I want to create a class called DefaultAttr which returns a default 
value for all attributes which haven't been given values yet. It will 
work like this:

 >> x = DefaultAttr(99)
 >> print x.foo
99
 >> print x.bar
99
 >> x.foo = 7
 >> print x.foo
7

I already have a similar class called DefaultDict which works similarly 
which I assume would be a good thing to use.

Lowell