anchor.diff:    }
   
     final String version = uri.pathSegments[2];
  -  if (version.isEmpty || version == 'latest') {
  +  if (version.isEmpty) {
       return new DocFilePath(package, null, null);
     }
     if (segmentCount == 3) {
  
positive.code:   if (redirectDartdocPages.containsKey(docFilePath.package)) {
      return redirectResponse(redirectDartdocPages[docFilePath.package]);
    }
    if (docFilePath.version == null) {
      final version = await dartdocBackend.getLatestVersion(docFilePath.package);
      if (version == null) {
        return redirectToSearch(docFilePath.package);
      } else {
        return redirectResponse(pkgDocUrl(docFilePath.package, version: version));
      }
    }
    if (docFilePath.path == null) {
      return redirectResponse('${request.requestedUri}/');
  
negative.code:   return notFoundHandler(request);
  }
  
  FutureOr<String> _effectiveVersion(DocFilePath docFilePath) {
    if (docFilePath.version == 'latest') {
      return dartdocBackend.getLatestVersion(docFilePath.package);
    } else {
      return docFilePath.version;
    }
  }
  
  class DocFilePath {
    final String package;
    final String version;
  