code: def insert(self, button):
          
          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
docs: Insert button to last row
  
          :param button:
          :return: self
          :rtype: :obj:`types.InlineKeyboardMarkup`