Use this method to add a new sticker to a set created by the bot. Returns True on success.
        :param user_id:
        :param name:
        :param png_sticker:
        :param emojis:
        :param mask_position:
        :return:

def add_sticker_to_set(self, user_id, name, png_sticker, emojis, mask_position=None):
        """
        Use this method to add a new sticker to a set created by the bot. Returns True on success.
        :param user_id:
        :param name:
        :param png_sticker:
        :param emojis:
        :param mask_position:
        :return:
        """
        return apihelper.add_sticker_to_set(self.token, user_id, name, png_sticker, emojis, mask_position)