Sender::getOpenedSessionChatId

protected function getOpenedSessionChatId(string $userSessionCode): ?string
{
	$session = new Session();
	$sessionLoadResult = $session->getLast(['USER_CODE' => $userSessionCode]);
	if (!$sessionLoadResult->isSuccess())
	{
		return null;
	}
	$sessionData = $session->getData();
	$chatId = $sessionData['CHAT_ID'];
	$closed = $sessionData['CLOSED'] === 'Y';
	if ($closed)
	{
		return null;
	}

	return $chatId;
}