protected function lib_rgba($args)
{
if ($color = $this->coerceColor($args[0])) {
$num = is_null($args[1]) ? $args[3] : $args[1];
$alpha = $this->assertNumber($num);
$color[4] = $alpha;
return $color;
}
list($r, $g, $b, $a) = $args;
return array("color", $r[1], $g[1], $b[1], $a[1]);
}