Always encode from unicode to bytes. In this direction, you get to choose the encoding.
>>> u'🐍'.encode('utf-8')
'\xf0\x9f\x90\x8d'
The other way is to decode from bytes to unicode. In this direction, you have to know what the encoding is.
>>> b'\xf0\x9f\x90\x8d'.decode('utf-8')
u'\U0001f40d'