code: def set_left_colon(self, show_colon):
          
          if show_colon:
              self.buffer[4] |= 0x04
              self.buffer[4] |= 0x08
          else:
              self.buffer[4] &= (~0x04) & 0xFF
              self.buffer[4] &= (~0x08) & 0xFF
docs: Turn the left colon on with show color True, or off with show colon
          False.  Only the large 1.2" 7-segment display has a left colon.