AttributeError: 'NoneType' object has no attribute 'span'

1、错误描述

E:PycharmProjectscmnvenvScriptspython.exe E:/PycharmProjects/cmn/venv/com.you.cmn/L.py
Traceback (most recent call last):
  File "E:/PycharmProjects/cmn/venv/com.you.cmn/L.py", line 3, in <module>
    a = re.match("@","454545@qq.com").span();
AttributeError: 'NoneType' object has no attribute 'span'

Process finished with exit code 1

2、错误原因

      在匹配@时，不是以这个开头，调用span()出现None.span()，出现报错

import re;

a = re.match("@","454545@qq.com").span();
print(a);

3、解决办法

（1）如果后面匹配不是以前面的字符，不使用span()

import re;

a = re.match("@","454545@qq.com");
print(a);

（2）以某个字符开头，调用span()

import re;

a = re.match("@","@454545@qq.com").span();
print(a);