code: def pixel(self, x, y, size=None):
          
          if (size is None):
              size = self.sz
          # Have we go to the smallest element?
          if (size <= 3):
              if (_middle(x, y)):
                  return (None)
              else:
                  return (0, 0, 0)
          divisor = size // 3
          if (_middle(x // divisor, y // divisor)):
              return None
          return self.pixel(x % divisor, y % divisor, divisor)
docs: Return color for a pixel.