Leafo\ScssPhp\Compiler::libFeatureExists PHP Method

    protected function libFeatureExists($args)
    {
        $string = $this->coerceString($args[0]);
        $name = $this->compileStringContent($string);
        return $this->toBool(array_key_exists($name, $this->registeredFeatures) ? $this->registeredFeatures[$name] : false);
    }