code: def display(self, buffer = None):
          
          if buffer != None:
              self._display_buffer( buffer )
          else:
              self._display_buffer( self._buffer )
docs: !
          \~english 
          Write buffer to physical display.
          @param buffer: Data to display，If <b>None</b> mean will use self._buffer data to display
          \~chinese 
          将缓冲区写入物理显示屏。
          @param buffer: 要显示的数据，如果是 <b>None</b>(默认) 将把 self._buffer 数据写入物理显示屏