code: public function setAttribute($key, $value)
      {
          if (in_array($key, $this->multipleHighloadBlockFields)) {
              $this->attributes[$key] = serialize($value);
  
              return $this;
          }
  
          parent::setAttribute($key, $value);
  
          return $this;
      }
docs: Set a given attribute on the model.
  
  @param  string  $key
  @param  mixed  $value
  @return $this