Set bulb type for specified group.

        Group must be int between 1 and 4.

        Type must be "rgbw" or "white".

        Alternatively, use constructor keywords group_1, group_2 etc. to set bulb types.

def set_group_type(self, group, bulb_type):
        """ Set bulb type for specified group.

        Group must be int between 1 and 4.

        Type must be "rgbw" or "white".

        Alternatively, use constructor keywords group_1, group_2 etc. to set bulb types.
        """
        if bulb_type not in ("rgbw", "white"):
            raise AttributeError("Bulb type must be either rgbw or white")

        self.group[group] = bulb_type
        self.has_white = "white" in self.group.values()
        self.has_rgbw = "rgbw" in self.group.values()