code: def color_xy(self):
          
          color_x = self._last_reading.get('color_x')
          color_y = self._last_reading.get('color_y')
          if color_x is not None and color_y is not None:
              return [float(color_x), float(color_y)]
          return None
docs: XY colour value: [float, float] or None
          :rtype: list float