 The genie chooses an urn in that room and randomly draws a ball from that urn.They then put the ball onto a conveyor belt, where the observer can observe the sequence of the balls but not the sequence of urns from which they were drawn.The genie has some procedure to choose urns; the choice of the urn for the "n"-th ball depends only upon a random number and the choice of the urn for the ("n" − 1)-th ball.