python str与bytes之间的转换

 # bytes object
  b = b"example"

  # str object
  s = "example"

  # str to bytes
  bytes(s, encoding = "utf8")

  # bytes to str
  str(b, encoding = "utf-8")

  # an alternative method
  # str to bytes
  str.encode(s)

  # bytes to str
  bytes.decode(b)