Leafo\ScssPhp\Compiler::libRgba PHP Method

    protected function libRgba($args)
    {
        if ($color = $this->coerceColor($args[0])) {
            $num = !isset($args[1]) ? $args[3] : $args[1];
            $alpha = $this->assertNumber($num);
            $color[4] = $alpha;
            return $color;
        }
        list($r, $g, $b, $a) = $args;
        return [Type::T_COLOR, $r[1], $g[1], $b[1], $a[1]];
    }