Airship\Engine\Lens::func PHP Method

    public function func(string $name, $func = null, $is_safe = ['html']) : self
    {
        if (empty($func)) {
            $func = '\\Airship\\LensFunctions\\' . $name;
        }
        $this->twigEnv->addFunction(new \Twig_SimpleFunction($name, $func, ['is_safe' => $is_safe]));
        return $this;
    }

 /**
  * Add a function to the lens
  *
  * @param string $name
  * @param callable $func
  */
 protected function addLensFunction(string $name, callable $func)
 {
     $this->airship_lens_object->func($name, $func);
 }