python ufeff
>>> f = open('file', mode='r', encoding='utf-8-sig')
>>> f.read()
'test'
>>> f = open('file', mode='r')
>>> f.read()
'\ufefftest'
ext
>>> f = open('file', mode='r', encoding='utf-8-sig')
>>> f.read()
'test'
>>> f = open('file', mode='r')
>>> f.read()
'\ufefftest'