迭代查找整个子目录，找出所有的子文档的路径

sub paths

def get_sub_time_paths(folder, root_vpath):
    """ 迭代查找整个子目录，找出所有的子文档的路径 """

    result = []
    for obj in folder.values(True, False):
        dc = obj.metadata
        if isinstance(obj, Folder):
            result.extend(get_sub_time_paths(obj, root_vpath))
        elif isinstance(obj, Page):
            result.append((
                dc.get('modified', 
                dc.get('created', '')),
                obj.vpath.replace(root_vpath + '/', ''),
            ))
    return result