def closest_left_node(tree, u):
    '\n    Returns the node that closest to u in a left-to-right sense.\n    '
    ret = NULL
    while ((u != NULL) and (ret == NULL)):
        ret = tree.left_sib(u)
        u = tree.parent(u)
    return ret
Returns the node that closest to u in a left-to-right sense.
def closest_left_node(tree, u):
    '\n    \n    '
    ret = NULL
    while ((u != NULL) and (ret == NULL)):
        ret = tree.left_sib(u)
        u = tree.parent(u)
    return ret