1. bytes object
    2. b = b"example"
    4. str object
    5. s = "example"
    7. str to bytes
    8. bytes(s, encoding = "utf8")
    10. bytes to str
    11. str(b, encoding = "utf-8")
    13. an alternative method
    14. str to bytes
    15. str.encode(s)
    17. bytes to str
    18. bytes.decode(b)