anchor.diff:  // Copyright 2015 The Chromium Authors. All rights reserved.
   // Use of this source code is governed by a BSD-style license that can be
   // found in the LICENSE file.
  -
  -import 'dart:collection';
   
   import 'package:flutter/foundation.dart';
   import 'package:vector_math/vector_math_64.dart';
  
positive.code:         library: 'gesture library',
          context: ErrorDescription('while routing a pointer event'),
          router: this,
          route: entry.route,
          event: event,
          informationCollector: () sync* {
            yield DiagnosticsProperty<PointerEvent>('Event', event, style: DiagnosticsTreeStyle.errorProperty);
  
negative.code: 
  /// A routing table for [PointerEvent] events.
  class PointerRouter {
    final Map<int, Map<PointerRoute, Matrix4>> _routeMap = <int, Map<PointerRoute, Matrix4>>{};
    final Map<PointerRoute, Matrix4> _globalRoutes = <PointerRoute, Matrix4>{};
  
    /// Adds a route to the routing table.
    ///
  