废话少说，放码过来：

def do_nothing(n):
    return n

l = [1, 2, 3]
t = (1, 2, 3)
mapList = map(do_nothing, l)

print('list:\n', list(l)) # [1, 2, 3]
print(list(l)) # [1, 2, 3]

print('tuple:\n', list(t)) # [1, 2, 3]
print(list(t)) # [1, 2, 3]

print('map:\n', list(mapList)) # [1, 2, 3]
print(list(mapList)) # []
# 吓得我：nmd, wsm!

后来经过实践，以及翻阅前面的章节（应该是 迭代器，不是就自己查吧顺便复习）然后得到了这么个东西，继续废话少说：

def do_nothing(n):
    return n

l = [1, 2, 3]
t = (1, 2, 3)
mapList = map(do_nothing, l)

print(next(mapList)) # 1
print(list(mapList)) # [2, 3]
print(list(mapList)) # []
# 原来如此！你个鸡贼