At any point during the trip, the Stack Count for the visited leaves and non-terminal vertices cannot subceed 1.

The southern wind Doth play the trumpet to his purposes, And by his hollow whistling in the leaves Foretells a tempest and a blustering day.

MISS JEMIMA! exclaimed Miss Pinkerton, in the largest capitals. Are you in your senses? Replace the Dixonary in the closet, and never venture to take such a liberty in future..

Oh, crickets! I can’t believe how forgetful I am.