s1 = '1+2'
s2 = 'print(666)'
print(eval(s1))
eval(s2)
print(exec(s1))
exec(s2)

3
666
None
666

print(self, *args, sep=' ', end='\n', file=None)  #*args接收参数, sep设置连接符  end是以什么结尾   file写入文件基本不用

print(1, 2, 3, sep = "$", end = "," )
print(4, 5)

1$2$3,4 5

l1 = "123"
print(id(l1))

3077824753992

print(help(str))   #查看str的所有用法

a1 = "adad"
def aa():
    print(666)
print(callable(a1))   #a1变量名为字符串不可调用
print(callable(aa))　　#aa变量名为函数,加括号可调用

False
True

for i in range(1,3):
    print(i)

1
2

l1 = [1, 2, 3]
l2 = iter(l1)   #将列表转为迭代器
print(next(l2))
print(next(l2))
print(next(l2))

1
2
3