closures in python

gistfile1.txt

    def getHeight(self, node=None):
        maxHeight = [0]

        def traverse(node, height):
            if not node:
                return

            height += 1

            if height > maxHeight[0]:
                maxHeight[0] = height

            traverse(node.left, height)
            traverse(node.right, height)

        if not node:
            node = self.root

        traverse(node, 0)
        return maxHeight[0]