anchor.diff:  
     bool _debugLocked = false; // used to prevent re-entrant calls to push, pop, and friends
   
  -  /// Looks up the route with the given name using [Navigator.onGenerateRoute],
  -  /// and then [push]es that route.
  -  ///
  -  /// Returns a Future that completes when the pushed route is popped.
  +  /// Push a named route onto the navigator.
  +  ///
  +  /// The route name will be passed to [Navigator.onGenerateRoute]. The returned
  +  /// route will be pushed into the navigator.
  +  ///
  +  /// Returns a [Future] that completes to the `result` value passed to [pop]
  +  /// when the pushed route is popped off the navigator.
  +  ///
  +  /// Typical usage is as follows:
  +  ///
  +  /// ```dart
  +  /// Navigator.of(context).pushNamed('/nyc/1776');
  +  /// ```
     Future<dynamic> pushNamed(String name) {
       assert(!_debugLocked);
       assert(name != null);
  
positive.code:   /// Ongoing gestures within the current route are canceled when a new route is
    /// pushed.
    ///
    /// Returns a Future that completes when the pushed route is popped.
    Future<dynamic> push(Route<dynamic> route) {
      assert(!_debugLocked);
      assert(() { _debugLocked = true; return true; });
  
negative.code:   /// The route name will be passed to that navigator's [onGenerateRoute]
    /// callback. The returned route will be pushed into the navigator.
    ///
    /// Returns a [Future] that completes to the `result` value passed to [pop]
    /// when the pushed route is popped off the navigator.
    ///
    /// Typical usage is as follows:
    ///
  