anchor.diff:    final int buildNumber = int.parse(change['build_number']);
     stats.buildNumber = buildNumber;
     final Set<String> configurations =
  -  results.map((change) => change['configuration'] as String)
  -  .toSet();
  +      results.map((change) => change['configuration'] as String).toSet();
     for (final configuration in configurations) {
  -    final record = await firestore.document('configurations/$configuration').get();
  +    final record =
  +        await firestore.document('configurations/$configuration').get();
       if (!record.exists || record.data.getString('builder') != builder) {
  -      await firestore.document('configurations/$configuration')
  +      await firestore
  +          .document('configurations/$configuration')
             .setData(DocumentData.fromMap({'builder': builder}));
         if (!record.exists) {
           info('Configuration document $configuration -> $builder created');
  
positive.code:       .get();
  
    // Find an existing change group with a blamelist that intersects this change.
     final startIndex = buildInfo['startIndex'];
     final endIndex = buildInfo['endIndex'];
  
    bool blamelistIncludesChange(DocumentSnapshot groupDocument) {
      var group = groupDocument.data;
  
negative.code:   final documentRef = firestore.document('builds/$builder:$endIndex');
    final record = await documentRef.get();
    if (!record.exists) {
      await documentRef.setData(DocumentData.fromMap(
          {'builder': builder, 'build_number': buildNumber, 'index': endIndex}));
      info('Created build record: '
          'builder: $builder, build_number: $buildNumber, index: $endIndex');
    } else if (record.data.getInt('index') != endIndex) {
      error(
          'Build $buildNumber of $builder had commit index ${record.data.getInt('index')},'
          'should be $endIndex.');
    }
    return {"startIndex": startIndex, "endIndex": endIndex};
  }
  
  Future<void> storeChange(Map<String, dynamic> change,
  