code: def scale_and_shift_cmap(self, scale_pct, shift_pct):
          
          rgbmap = self.get_rgbmap()
          rgbmap.scale_and_shift(scale_pct, shift_pct)
docs: Stretch and/or shrink the color map.
          See :meth:`ginga.RGBMap.RGBMapper.scale_and_shift`.