having list attribute to track max size

[ankitks.mital at gmail.com]

Lets say I have a dynamic list class (may be extended from list),
where I add and remove items during program.
a = []
a.append(1)
....

I am trying to find is there easy way keep track of 'maximum size of
list reached"
so for example len(a) goes from 0->3->4->3
If I call a.max_size_ever(), I will get 4

Thanks.