Use this method to broadcast text message to all users of bot.

        :param bot: bot that will push user
        :type bot: Bot
        :param channel_type: one of [telegram, facebook, slack]
        :type channel_type: str
        :param text: text message
        :type text: str

def broadcast(self, bot, channel_type, text):
        """
        Use this method to broadcast text message to all users of bot.

        :param bot: bot that will push user
        :type bot: Bot
        :param channel_type: one of [telegram, facebook, slack]
        :type channel_type: str
        :param text: text message
        :type text: str
        """
        self.client.broadcast.__getattr__(bot.name).__call__(_method="POST",
                                                        _params=dict(channel=channel_type),
                                                        _json=dict(message=text))