anchor.diff:  
         bagel-serial = callPackage ./bagel { mpi = null; blas = self.mkl; };
   
  -      cefine = callPackage ./cefine { };
  +      cefine = self.nullable self.turbomole (callPackage ./cefine { });
   
         cfour = callPackage ./cfour { };
   
  
positive.code: 
        f2c = callPackage ./f2c { };
  
        tests = {
          cfour = callPackage ./tests/cfour { };
          cp2k = callPackage ./tests/cp2k { };
          bagel = callPackage ./tests/bagel { };
  
negative.code:           sha256 = sha256;
          };
  
        # Return null if x == null otherwise return the argument
        nullable = x: ret: if x == null then null else ret;
  
        #
        # Applications
        #
  