[Python] bytes 转换成 str

b = b"example"    # bytes object
s = "example"     # str object
sb = bytes(s, encoding = "utf8")    # str to bytes
或者：sb = str.encode(s)             # str to bytes
bs = str(b, encoding = "utf8")      # bytes to str
或者：bs = bytes.decode(b)           #  bytes to str