The main program leads Kara to the tree, calling the method invertLeaf
before each step. This method tests whether Kara is on a leaf; if yes, Kara picks it up, if no, Kara puts one down.
def invertLeaf(): if kara.onLeaf(): kara.removeLeaf() else: kara.putLeaf() invertLeaf() while not kara.treeFront(): kara.move() invertLeaf()