Secretary::isUserInChat

static function isUserInChat($chatId, $userId = 0): bool
{
	$chat = new CIMChat($userId);
	$chatData = $chat->GetChatData(['ID' => $chatId]);
	if (isset($chatData['userInChat'][$chatId]) && in_array((int)$userId, $chatData['userInChat'][$chatId], true))
	{
		return true;
	}
	return false;
}