作业要求：下述所有代码画图以及分析代码执行流程

1、以定义阶段为准，先画出名称空间的嵌套关系图

2、然后找到调用函数的位置，写出函数调用时代码的执行过程，涉及到名字的查找时，参照1中画好

的嵌套图，标明查找顺序，一层一层直到找到位置

===================题目一===================

input=333
def func():
input=444
func()
print(input)

===================题目二===================

def func():
print(x)
x=111

func()

===================题目三===================

x=1
def func():
print(x)

def foo():
x=222
func()

foo()

===================题目四===================

input=111
def f1():
def f2():
# input=333
print(input)
input=222

f2()

f1()

===================题目五===================

x=111
def func():
print(x) #
x=222

func()

===================题目六===================

x=111

def foo():
print(x,)

def bar():
print(x)

foo()
bar()

===================题目七===================

x=1
def func2():
func1()

x=2
def func1():
print(x)

x=3

func2()

===================题目八===================

1、如下全局变量记录了当前登录用户，编写登录功能，一旦用户登录成功，则将全局变量赋值为当前登录的用户名

login_user=None
login_user=None
def login():
    username=input('用户名：')
    password=input('密码：')
    with open('logn.txt',mode='rt',encoding='utf-8') as f:
        for line in f:
            user,pwd=line.strip().split(':')
            if username==user and password==pwd:
                login_user = username
                print(login_user,'登陆成功')
                return
            else:
                print('登陆失败')
login()

2、针对之前编写的查询余额的功能，添加额外的逻辑：如果用户没有登录，则先执行登录功能

def check_money(username):
    dic = {}
    with open('a.txt', 'r', encoding='utf-8') as f:
        for line in f:
            user, money = line.strip().split(':')
            dic[user] = float(money)
    if not user_info.get('user'):
        login()
    if username not in dic:
        return
    return dic.get(username)