/**
  * Returns <b>true</b> when the given node is an abstract method.
  *
  * @param PHP_PMD_AbstractNode $node The context method or function instance.
  *
  * @return boolean
  */
 private function _isAbstractMethod(PHP_PMD_AbstractNode $node)
 {
     if ($node instanceof PHP_PMD_Node_Method) {
         return $node->isAbstract();
     }
     return false;
 }