code: def convert_to_pixels(self, value):
          
          percent = ((value - self._start) / self._extent)
          return percent * (self.get_scale_length() - self._sliderlength) + self._sliderlength / 2
docs: Convert value in the scale's unit into a position in pixels.
          
          :param value: value to convert
          :type value: float
          
          :return: the corresponding position in pixels
          :rtype: float