def get_chat_ids(self):
        """Returns unique chat IDs from `/start` command messages sent to our bot by users.
        Those chat IDs can be used to send messages to chats.

        :rtype: list
        """
        updates = self.get_updates()
        chat_ids = []
        if updates:
            for update in updates:
                message = update['message']
                if message['text'] == '/start':
                    chat_ids.append(message['chat']['id'])
        return list(set(chat_ids))