class Printer:

$"""$A Printer.

$==$ Attributes $===$

message: the message to print

$4"$n$"$

message: str

def$\_\_$init$\_($self$,$ message: str$)$ None:

self.message $=$ message

def print$\_$message$($self$)$:

$""$ "Prints a message.

$"$n$""$

print$($self$.$message$)$

class MysteryPrinter$($Printer$)$:

def$\_\_$init$\_($self$,$ message: str$)$ None:

Printer.$($self$,$ message $+$ message$)$

class DoublePrinter$($MysteryPrinter$)$:

def print$\_$message$($self$)$:

print$($self$.$message $+$ self.message$)$

if $==\text{'}\text{'}$:

$m1\frac{?}{b}=ar(Pr{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}er){(}^{\text{'}}hell{o}^{\text{'}})$

$m2=$ MysteryPrinter $(\text{'}$good$\text{'})$

m$3=$ DoublePrinter $(\text{'}$bye$\text{'})$

m$1.$print$\_$message$()$

m$2.$print$\_$message$()$

m$3.$print$\_$message$()$