anchor.diff:  { lib, fetchFromGitHub, python3Packages, file, less, highlight
  -, imagePreviewSupport ? true, w3m ? null}:
  -
  -with lib;
  -
  -assert imagePreviewSupport -> w3m != null;
  +, imagePreviewSupport ? true, w3m }:
   
   python3Packages.buildPythonApplication rec {
  -  name = "ranger-${version}";
  +  pname = "ranger";
     version = "1.9.3";
   
     src = fetchFromGitHub {
  
positive.code: 
    LC_ALL = "en_US.UTF-8";
  
    checkInputs = with python3Packages; [ pytest ];
    propagatedBuildInputs = [ file ]
      ++ lib.optionals (imagePreviewSupport) [ python3Packages.pillow ];
  
    checkPhase = ''
      py.test tests
    '';
  
    preConfigure = ''
      ${lib.optionalString (highlight != null) ''
  
negative.code:     # give file previews out of the box
      substituteInPlace ranger/config/rc.conf \
        --replace "#set preview_script ~/.config/ranger/scope.sh" "set preview_script $out/share/doc/ranger/config/scope.sh"
    '' + lib.optionalString imagePreviewSupport ''
      substituteInPlace ranger/ext/img_display.py \
        --replace /usr/lib/w3m ${w3m}/libexec/w3m
  
  