classes.py

class Television:
    """
    Class for Television objects.
    """
    MIN_CHANNEL = 0     # Minimum TV channel
    MAX_CHANNEL = 3     # Maximum TV channel

    MIN_VOLUME = 0      # Minimum TV volume
    MAX_VOLUME = 2      # Maximum TV volume

    def __init__(self) -> None:
        """
        Initialize a Television object.
        """
        self.__channel: int = Television.MIN_CHANNEL
        self.__volume: int = Television.MIN_VOLUME
        self.__status: bool  = False

    def power(self) -> None:
        """
        Function turns TV on and off.
        """
        if self.__status:
            self.__status = False
        else:
            self.__status = True

    def channel_up(self) -> None:
        """
        Function raise the current channel.
        """
        if self.__status:
            if self.__channel < Television.MAX_CHANNEL:
                self.__channel += 1
            else:
                self.__channel = Television.MIN_CHANNEL

    def channel_down(self) -> None:
        """
        Function lowers the current channel.
        """
        if self.__status:
            if self.__channel > Television.MIN_CHANNEL:
                self.__channel -= 1
            else:
                self.__channel = Television.MAX_CHANNEL

    def volume_up(self) -> None:
        """
        Function raises the current volume.
        """
        if self.__status:
            if self.__volume < Television.MAX_VOLUME:
                self.__volume += 1

    def volume_down(self) -> None:
        """
        Function lowers the current volume.
        """
        if self.__status:
            if self.__volume > Television.MIN_VOLUME:
                self.__volume -= 1

    def __str__(self) -> str:
        """
        Overrides normal __str__ functionality to return the status of the Television object.
        """
        return f'TV status: Is on = {self.__status}, Channel = {self.__channel}, Volume = {self.__volume}'