anchor.diff:    ///
     /// Returns true if successful or false if the header's condition doesn't fit
     /// into a single status file and needs to be manually split by the user.
  -  bool add(String fromDir, String header, String entry) {
  +  bool add(String fromFile, String fromDir, String header, String entry) {
       var toDir = toTwoDirectory(fromDir);
   
       // Figure out which status file it goes into.
  
positive.code:   }
  
    // If any entries need manual splitting, let the user know.
    for (var dir in entriesToMove._todoHeaders.keys) {
      var destination = "$dir.status";
      var headers = entriesToMove._todoHeaders[dir];
      var splits = headers.map((header) {
        var files =
            filesForHeader(header).map((file) => bold("${dir}_$file")).join(", ");
        return "Need to manually split status file section in ${bold(destination)}"
            " across files $files:\n    $header";
      }).toList();
  
      if (splits.isNotEmpty) todos[destination] = splits;
    }
  }
  
  
negative.code:       // manually split it up into multiple sections first.
        // TODO(rnystrom): Would be good to automate this, though it requires
        // being able to work with condition expressions directly.
        var statusRelative = p.relative(fromFile, from: testRoot);
        _todoHeaders.putIfAbsent(statusRelative, () => new Set()).add(header);
        return false;
      }
  
  