Knights or knaves?

There are two identical twins one of whom always lies and the other who always tells the truh.One is named john.
suppose you meet the two brothers for the first time and have not yet asked either of them any questions.You want to know whether john lies or tells the truth.(neglect which one is john).you can ask only one question which has only three words and is answered as yes or no.

What three-worded,yes-or-no question would disclose whether john lies?

Are you a Smullyan fan too?

And the answer is "Are you John"