anchor.diff:  
   * libsass $libsassRevision and sassc $sasscRevision compiled with $gPlusPlusVersion.
   * Dart Sass $dartSassRevision on Dart $dartVersion and Node $nodeVersion.
  -* Ruby Sass $rubySassRevision on $rubyVersion.
   
   """);
   
  
positive.code:           environment: {"SASS_LIBSASS_PATH": p.absolute(libsass)}));
    log("");
  
    var ruby = await cloneOrPull('https://github.com/sass/ruby-sass');
    log("");
  
    var libsassRevision = await _revision(libsass);
    var sasscRevision = await _revision(sassc);
    var dartSassRevision = await _revision('.');
    var rubySassRevision = await _revision(ruby);
    var gPlusPlusVersion = await _version("g++");
    var nodeVersion = await _version("node");
    var rubyVersion = await _version("ruby");
  
    var perf = File("perf.md").readAsStringSync();
    perf = perf.replaceFirst(RegExp(r"This was tested against:\n\n[^]*?\n\n"), """
  
negative.code:     buffer.writeln('* ${_compare(nativeExecutableTime, sasscTime)} libsass');
      buffer.writeln(
          '* ${_compare(nativeExecutableTime, nodeTime)} Dart Sass on Node');
      buffer.writeln();
      log('');
    }
  