code: public function push($key, $value)
      {
          $items = $this->get($key);
          if (!is_array($items)) {
              throw new UnexpectedValueException("Expected the target to be array, got " . gettype($items));
          }
  
          $items[] = $value;
          $this->set($key, $items);
      }
docs: {@inheritdoc}