Fixed a pylint(E1101) error 

Seems like pylint complains about a LookUpDict not having a member,
which is probably created at runtime. The examples still run, but it's
confusing for people using pylint. I know the warning can be supressed, but
it's a tiny change so it's easy for you to patch it upstream.

http://pylint-messages.wikidot.com/messages:e1101