英文文档：
locals()
update and return a dictionary representing the current local symbol table. free variables are returned by locals() when it is called in function blocks, but not in class blocks.
说明：
1. 函数功能返回当前作用域内的局部变量和其值组成的字典，与globals函数类似(返回全局变量)
>>> locals()
{‘__package__’: none, ‘__loader__’: , ‘__doc__’: none, ‘__name__’: ‘__main__’, ‘__builtins__’: , ‘__spec__’: none}
>>> a = 1
>>> locals() # 多了一个key为a值为1的项
{‘__package__’: none, ‘__loader__’: , ‘a’: 1, ‘__doc__’: none, ‘__name__’: ‘__main__’, ‘__builtins__’: , ‘__spec__’: none}
2. 可用于函数内。
>>> def f():
print(‘before define a ‘)
print(locals()) #作用域内无变量
a = 1
print(‘after define a’)
print(locals()) #作用域内有一个a变量，值为1
>>> f
>>> f()
before define a
{}
after define a
{‘a’: 1}
3. 返回的字典集合不能修改。
>>> def f():
print(‘before define a ‘)
print(locals()) # 作用域内无变量
a = 1
print(‘after define a’)
print(locals()) # 作用域内有一个a变量，值为1
b = locals()
print(‘b[“a”]: ‘,b[‘a’])
b[‘a’] = 2 # 修改b[‘a’]值
print(‘change locals value’)
print(‘b[“a”]: ‘,b[‘a’])
print(‘a is ‘,a) # a的值未变
>>> f()
before define a
{}
after define a
{‘a’: 1}
b[“a”]: 1
change locals value
b[“a”]: 2
a is 1
>>>