   public function search(int $data) {
      if ($this->isEmpty()) {
         return FALSE;
      }

      $node = $this->root;

      while ($node) {
         if ($data > $node->data) {
            $node = $node->right;
         } elseif ($data < $node->data) {
            $node = $node->left;
         } else {
            break;
         }
      }

      return $node;
   }
