protected function classify(TextBlock $prev, TextBlock $curr, TextBlock $next)
 {
     $isContent = false;
     if ($curr->getLinkDensity() <= 0.333) {
         if ($prev->getLinkDensity() <= 0.555) {
             if ($curr->getWordCount() <= 16) {
                 if ($next->getWordCount() <= 15) {
                     if ($prev->getWordCount() > 4) {
                         $isContent = true;
                     }
                 } else {
                     $isContent = true;
                 }
             } else {
                 $isContent = true;
             }
         } else {
             if ($curr->getWordCount() <= 40) {
                 if ($next->getWordCount() > 17) {
                     $isContent = true;
                 }
             } else {
                 $isContent = true;
             }
         }
     }
     return $curr->setIsContent($isContent);
 }