code: def set_pixel(self, x, y, value):
          
          if x < 0 or x > 7 or y < 0 or y > 7:
              # Ignore out of bounds pixels.
              return
          # Set green LED based on 1st bit in value.
          self.set_led(y * 16 + x, 1 if value & GREEN > 0 else 0)
          # Set red LED based on 2nd bit in value.
          self.set_led(y * 16 + x + 8, 1 if value & RED > 0 else 0)
docs: Set pixel at position x, y to the given value.  X and Y should be values
          of 0 to 8.  Value should be OFF, GREEN, RED, or YELLOW.