import codecs

def decode(some_bytes):
    s = "".join("\\x{:02x}".format(i) for i in some_bytes)
    return (s, len(some_bytes))

def encode(some_string):
    if len(some_string) %4 != 0:
        raise Exception("Expected only four-character escape sequences")
    chars = []
    for i in range(0, len(some_string), 4):
        symbol = some_string[i:i+4]
        if symbol[:2] != "\\x":
            raise Exception("Expected only \\x escape sequences")
        chars.append(int(symbol[2:], 16))
    return (bytes(chars), len(some_string))


AllEscapes = codecs.CodecInfo(encode, decode, name="all_escapes")

codecs.register(lambda name: AllEscapes if name == "all_escapes" else None)

x = b"Hello, World!"
print(x.decode("all_escapes"))
#result: \x48\x65\x6c\x6c\x6f\x2c\x20\x57\x6f\x72\x6c\x64\x21

print(x.decode("all_escapes").encode("all_escapes"))
#result: b'Hello, World!'