anchor.diff:    # available as `pythonPackages.tkinter` and can be used as any other Python package.
     python = python2;
     python2 = python27;
  -  python3 = python35;
  +  python3 = python36;
   
     # Python interpreter that is build with all modules, including tkinter.
     # These are for compatibility and should not be used inside Nixpkgs.
  
positive.code: 
    python34Packages = python34.pkgs;
  
    python35Packages = recurseIntoAttrs python35.pkgs;
  
    python36Packages = python36.pkgs;
  
    pypyPackages = pypy.pkgs;
  
  
negative.code:     self = python33;
      inherit (darwin) CF configd;
    };
    python34 = callPackage ../development/interpreters/python/cpython/3.4 {
      inherit (darwin) CF configd;
      self = python34;
    };
    python35 = callPackage ../development/interpreters/python/cpython/3.5 {
      inherit (darwin) CF configd;
      self = python35;
    };
    python36 = callPackage ../development/interpreters/python/cpython/3.6 {
      inherit (darwin) CF configd;
      self = python36;
  