    def __init__(self, screen, x, y, r, bg=Screen.COLOUR_BLACK, **kwargs):
        """
        :param screen: The Screen being used for the Scene.
        :param x: X coordinate for the centre of the clock.
        :param y: Y coordinate for the centre of the clock.
        :param r: Radius of the clock.
        :param bg: Background colour for the clock.

        Also see the common keyword arguments in :py:obj:`.Effect`.
        """
        super().__init__(screen, **kwargs)
        self._x = x
        self._y = y
        self._r = r
        self._bg = bg
        self._old_time = None
:param screen: The Screen being used for the Scene.
:param x: X coordinate for the centre of the clock.
:param y: Y coordinate for the centre of the clock.
:param r: Radius of the clock.
:param bg: Background colour for the clock.

Also see the common keyword arguments in :py:obj:`.Effect`.
asciimatics/effects.py