/**
  * Should the import be skipped?
  *
  * @return boolean|null
  */
 private function Skip($path, $env)
 {
     $path = Less_Parser::winPath(realpath($path));
     if ($path && Less_Parser::FileParsed($path)) {
         if (isset($this->currentFileInfo['reference'])) {
             return true;
         }
         return !isset($this->options['multiple']) && !$env->importMultiple;
     }
 }