anchor.diff:        };
   
         sagenb = self.callPackage ./sagenb.nix {
  -        mathjax = nodePackages_8_x.mathjax;
  +        mathjax = nodePackages.mathjax;
         };
   
         sagedoc = self.callPackage ./sagedoc.nix {
  
positive.code: }:
  
  let
    inherit (nixpkgs) fetchpatch fetchurl symlinkJoin callPackage nodePackages_8_x;
  
    # https://trac.sagemath.org/ticket/15980 for tracking of python3 support
    python = nixpkgs.python2.override {
  
negative.code:         inherit pythonEnv;
          inherit sage-src openblas-blas-pc openblas-cblas-pc openblas-lapack-pc pynac singular;
          pkg-config = nixpkgs.pkgconfig; # not to confuse with pythonPackages.pkgconfig
          three = nodePackages.three;
        };
  
        sage = self.callPackage ./sage.nix { };
  