protected function lib_spin($args)
{
list($color, $delta) = $this->colorArgs($args);
$hsl = $this->toHSL($color);
$hsl[1] = $hsl[1] + $delta % 360;
if ($hsl[1] < 0) {
$hsl[1] += 360;
}
return $this->toRGB($hsl);
}