Python traversal folder -- depth first (DFS)/breadth first (BFS)

import osdef BFS_Dir(path, dirCallback = None, fileCallback = None):    queue = []    ret = []    queue.append(path);    while len(queue) > 0:        tmp = queue.pop(0)        if(os.path.isdir(tmp)):            ret.append(tmp)            for item in os.listdir(tmp):                queue.append(os.path.join(tmp, item))            if dirCallback:                dirCallback(tmp)        elif(os.path.isfile(tmp)):            ret.append(tmp)            if fileCallback:                fileCallback(tmp)    return retdef DFS_Dir(path, dirCallback = None, fileCallback = None):    stack = []    ret = []    stack.append(path);    while len(stack) > 0:        tmp = stack.pop(len(stack) - 1)        if(os.path.isdir(tmp)):            ret.append(tmp)            for item in os.listdir(tmp):                stack.append(os.path.join(tmp, item))            if dirCallback:                dirCallback(tmp)        elif(os.path.isfile(tmp)):            ret.append(tmp)            if fileCallback:                fileCallback(tmp)    return retdef printDir(path):    print "dir: " + pathdef printFile(path):    print "file: " + pathb = BFS_Dir(r'C:\tmp', printDir, printFile)d = DFS_Dir(r'C:\tmp', printDir, printFile)