code: def get_rgbval(self, index):
          
          assert (index >= 0) and (index <= self.maxc), \
              RGBMapError("Index must be in range 0-%d !" % (self.maxc))
          index = self.sarr[index].clip(0, self.maxc)
          return (self.arr[0][index],
                  self.arr[1][index],
                  self.arr[2][index])
docs: Return a tuple of (R, G, B) values in the 0-maxc range associated
          mapped by the value of `index`.