anchor.diff:  final _detectedTagPrefixes = <String>{
     ...allowedTagPrefixes.expand((s) => [s, '-$s', '+$s']),
   };
  -
  -final _logger = Logger('search.search_service');
   
   /// Statistics about the index content.
   class IndexInfo {
  
positive.code: 
  import 'package:clock/clock.dart';
  import 'package:json_annotation/json_annotation.dart';
  import 'package:logging/logging.dart';
  
  import '../shared/tags.dart';
  
  
negative.code:     return p;
    }
  
    /// Appends [other] predicate to the current set of tags, and returns a new
    /// [TagsPredicate] instance.
    ///
    /// If there are conflicting tag predicates, the [other] takes precedence over
    /// this [TagsPredicate].
    TagsPredicate appendPredicate(TagsPredicate other) {
      final p = TagsPredicate();
      p._values.addAll(_values);
      p._values.addAll(other._values);
  