...and in the afterlife appeared at the front of two identical unmarked doors in a huge wall you can't get around any other way. One door leads to heaven and other to hell, but you don't know which. There is one set of twins standing close together, one is a constant liar, the other is a truth teller, but you don't know who is which. You got one chance to answer one question directed at both of them, and one chance to open one door. What would your question be that both of them would point you to correct door to heaven?