python 'is not' operator

Question

I notice there is a comparison operator is not. Should I literally translate it into

!= 

instead of

== not

Answer 1

To expand on what Ignacio said:

a == b and a != b test whether two objects have the same value. You can override an object's __eq__ and __ne__ methods to determine what that means.

a is b and a is not b test whether two objects are the same thing. It's like doing id(a) == id(b)