def hex(self, value):
        """Setter for colour in Hex format "#RRGGBB"."""

        if Colour.is_hex(value):
            c = value.lstrip("#")
            self._rgb = tuple(int(c[i:i + 2], 16) for i in (0, 2, 4))
        else:
            raise ValueError("'{0}' is not a valid Hex colour!".format(value))