code: def set_decimal(self, pos, decimal):
          
          if pos < 0 or pos > 3:
              # Ignore out of bounds digits.
              return
          # Jump past the colon at position 2 by adding a conditional offset.
          offset = 0 if pos < 2 else 1
  
          # Calculate the correct position depending on orientation
          if self.invert:
              pos = 4-(pos+offset)
          else:
              pos = pos+offset
  
          # Set bit 7 (decimal point) based on provided value.
          if decimal:
              self.buffer[pos*2] |= (1 << 7)
          else:
              self.buffer[pos*2] &= ~(1 << 7)
docs: Turn decimal point on or off at provided position.  Position should be
          a value 0 to 3 with 0 being the left most digit on the display.  Decimal
          should be True to turn on the decimal point and False to turn it off.