This sentence in the deque docs (https://docs.python.org/2/library/collections.html#collections.deque) is not accurate: 

"Deques are a generalization of stacks and queues ..."

Deques are a _specialization_ of stacks and queues. Every deque is-a stack and is-a queue, but saying that "deques generalize stacks and queues" reverses this relationship.

On the surface it might seem minor, but I think it's worth correcting in this case since the "is-a" relationship is so fundamental in computer science. Besides, I'd like to think Python's awesome documentation is above using words to mean the opposite of what they mean :)