pypi有现成的库emoji来处理emoji字符串
安装：
pip install emoji --upgrade
eg：
>> import emoji
>> print(emoji.emojize('Python is :thumbs_up:'))
Python is ?
>> print(emoji.emojize('Python is :thumbsup:', use_aliases=True))
Python is ?
>> print(emoji.demojize('Python is ?'))
Python is :thumbs_up:
