anchor.diff:        includes = map (x: [x.key (baseNameOf (toString x.key))])
           (findLhs2TeXIncludes {rootFile = source;});
       };
  -  
  +
     animateDot = dotGraph: nrFrames: pkgs.stdenv.mkDerivation {
       name = "dot-frames";
       builder = ./animatedot.sh;
  
positive.code: 
      builtins.genericClosure {
        startSet = [{key = rootFile;}];
        
        operator =
          {key, ...}:
  
  
negative.code:       builder = ./dot2ps.sh;
        inherit dotGraph;
        buildInputs = [
          pkgs.perl pkgs.graphviz pkgs.ghostscript
        ];
      };
  
  