def only_grey(self):
        rawval = (self.r + self.b + self.g) / 3
        n = min(range(len(_grey_vals)), key=[abs(x-rawval) for x in _grey_vals].__getitem__)
        return n+232
Finds the greyscale color.
dataset/ETHPy150Open tomerfiliba/plumbum/plumbum/colorlib/names.py/FindNearest.only_grey