    def __init__(self, height, width, colours):
        """
        :param height: Height of the box to contain the plasma.
        :param width: Width of the box to contain the plasma.
        :param colours: Number of colours the screen supports.
        """
        super().__init__(height, width)
        self._palette = self._palette_256 if colours >= 256 else self._palette_8
        self._t = 0
:param height: Height of the box to contain the plasma.
:param width: Width of the box to contain the plasma.
:param colours: Number of colours the screen supports.
asciimatics/renderers/plasma.py