GDS\Entity::__set PHP Method

    public function __set($str_key, $mix_value)
    {
        $this->arr_data[$str_key] = $mix_value;
    }

 public function __set($key, $value)
 {
     $definition = $this->getDefinition();
     if (isset($definition[$key])) {
         parent::__set($key, $value);
     } else {
         throw new Exception('Error ' . $key . ' is not settable.');
     }
 }