code: public function file($name)
      {
          $usephp = c::get('twig.usephp', true);
          $base = str_replace('\\', '/', $this->kirby->roots()->templates().'/'.$name);
          $twig = $base . '.twig';
          $php  = $base . '.php';
  
          // only check existing files if PHP template support is active
          if ($usephp and !is_file($twig) and is_file($php)) {
              return $php;
          } else {
              return $twig;
          }
      }
docs: Returns a template file path by name
  @param string $name
  @return string