Practice Python's yield from expression

binary-tree-traverse.py

class Node:
    def __init__(self, v):
        self.v = v
        self.l = None
        self.r = None
    def __repr__(self):
        return '<Node %d>' % self.v


def children(node):
    if node.l:
        yield node.l
    if node.r:
        yield node.r


def traverse(root):
    def _traverse(node, path):
        if node.l is None and node.r is None:
            yield path + [node.v]
        for child in children(node):
            yield from _traverse(child, path + [node.v])

    yield from _traverse(root, [])


tree = Node(1)
tree.l = Node(2)
tree.r = Node(3)
tree.l.l = Node(4)
tree.l.r = Node(5)

ans = traverse(tree)
print(list(ans))