/**
  * Return the instance of the compiler
  *
  * @param sfEventDispatcher $dispatcher Event dispatcher
  * @return sfSassCompiler The instance
  */
 public static function getInstance(sfEventDispatcher $dispatcher)
 {
     if (!self::$instance) {
         self::$instance = new sfSassCompilerDefault($dispatcher);
     }
     return self::$instance;
 }