anchor.diff:    # python function with default python interpreter
     buildPythonPackage = pythonPackages.buildPythonPackage;
   
  -  pythonPackages = python27Packages;
  -
     # `nix-env -i python-nose` installs for 2.7, the default python.
     # Therefore we do not recurse into attributes here, in contrast to
     # python27Packages. `nix-env -iA python26Packages.nose` works
  
positive.code:     inherit pkgs;
      python = python34;
    });
  
    python32Packages = import ./python-packages.nix {
      inherit pkgs;
      python = python32;
    };
  
    python27Packages = lib.hiPrioSet (recurseIntoAttrs (import ./python-packages.nix {
      inherit pkgs;
      python = python27;
    }));
  
    pypyPackages = recurseIntoAttrs (import ./python-packages.nix {
      inherit pkgs;
  
negative.code:     llvm = llvm_33 ;
    };
  
    python = python2;
    python2 = python27;
    python3 = python34;
  
    # pythonPackages further below, but assigned here because they need to be in sync
    pythonPackages = python2Packages;
    python2Packages = python27Packages;
    python3Packages = python34Packages;
  
    pythonFull = python2Full;
    python2Full = python27Full;
  
    python26 = callPackage ../development/interpreters/python/2.6 { db = db47; };
    python27 = callPackage ../development/interpreters/python/2.7 { };
    python32 = callPackage ../development/interpreters/python/3.2 { };
    python33 = callPackage ../development/interpreters/python/3.3 { };
    python34 = hiPrio (callPackage ../development/interpreters/python/3.4 { });
  
    pypy = callPackage ../development/interpreters/pypy/2.3 { };
  
    python26Full = callPackage ../development/interpreters/python/wrapper.nix {
      extraLibs = [];
      postBuild = "";
  