EventManager::obtainEntity

static function obtainEntity($entity)
{
	// define entity
	if ($entity instanceof Entity)
	{
		// ok
	}
	elseif (is_subclass_of($entity, DataManager::class))
	{
		$entity = $entity::getEntity();
	}
	elseif (is_subclass_of($entity, EntityObject::class))
	{
		$dataClass = $entity::$dataClass;
		$entity = $dataClass::getEntity();
	}
	else
	{
		throw new ArgumentException('Unknown entity value');
	}

	return $entity;
}