stack = []

def search(root, v):
    global stack
    stack.append(root.info)
    if root.info == v:
        print(stack)
        return
    if root.left is not None:
        search(root.left, v)
    if root.right is not None:
        search(root.right, v)
    stack.pop()
    pass

def lca(root, v1, v2):
    search(root,v1)
    print(stack)

[4, 2, 1]
[4]