anchor.diff:      databaseModule = perlPackages.DBDPg;
       sqitchModule = perlPackages.AppSqitch;
     };
  -
  -  ### DEVELOPMENT / PYTHON MODULES
  -
  -  # Python package sets.
  -
  -  python27Packages = lib.hiPrioSet (recurseIntoAttrs python27.pkgs);
  -
  -  python34Packages = python34.pkgs;
  -
  -  python35Packages = python35.pkgs;
  -
  -  python36Packages = recurseIntoAttrs python36.pkgs;
  -
  -  pypyPackages = pypy.pkgs;
   
     ### DEVELOPMENT / R MODULES
   
  
positive.code:   python = python2;
    python2 = python27;
    python3 = python36;
  
    # Python interpreter that is build with all modules, including tkinter.
    # These are for compatibility and should not be used inside Nixpkgs.
  
negative.code:     self = python36;
    };
  
    pypy27 = callPackage ../development/interpreters/python/pypy/2.7 {
      self = pypy27;
      python = python27.override{x11Support=true;};
      db = db.override { dbmSupport = true; };
    };
  
    # Python package sets.
    python27Packages = lib.hiPrioSet (recurseIntoAttrs python27.pkgs);
    python34Packages = python34.pkgs;
    python35Packages = python35.pkgs;
    python36Packages = recurseIntoAttrs python36.pkgs;
    pypyPackages = pypy.pkgs;
  
    # Should eventually be moved inside Python interpreters.
    python-setup-hook = callPackage ../development/interpreters/python/setup-hook.nix { };
  
    python2nix = callPackage ../tools/package-management/python2nix { };
  
  