/**
  * Get cached time expression parser instance. Instance is shared across all models.
  */
 public function getTimeExpressionParser()
 {
     if (!BundlableLabelableBaseModelWithAttributes::$s_tep) {
         BundlableLabelableBaseModelWithAttributes::$s_tep = new TimeExpressionParser();
     }
     return BundlableLabelableBaseModelWithAttributes::$s_tep;
 }