code: def scale_to_vols(self, vols):
          
  
          [self.ells[i].scale_to_vol(vols[i]) for i in range(self.nells)]
          self.vols = np.array(vols)
          self.expands = np.array([self.ells[i].expand
                                   for i in range(self.nells)])
          vol_tot = sum(vols)
          self.expand_tot *= vol_tot / self.vol_tot
          self.vol_tot = vol_tot
docs: Scale ellipoids to a corresponding set of
          target volumes.