Insert button to last row

        :param button:
        :return: self
        :rtype: :obj:`types.InlineKeyboardMarkup`

def insert(self, button):
        """
        Insert button to last row

        :param button:
        :return: self
        :rtype: :obj:`types.InlineKeyboardMarkup`
        """
        if self.inline_keyboard and len(self.inline_keyboard[-1]) < self.row_width:
            self.inline_keyboard[-1].append(button)
        else:
            self.add(button)
        return self