使用正则表达式将标题中，单词首字母大写

import re
def titlecase(s):
    return re.sub(r"[A-Za-z]+('[A-Za-z]+)?",
     lambda mo: mo.group(0)[0].upper() +
     mo.group(0)[1:].lower(),
     s)
text = "He's an engineer, isn't he?"
print(titlecase(text))