anchor.diff:  // Use of this source code is governed by a BSD-style license that can be
   // found in the LICENSE file.
   
  -import 'dart:math';
  -
   import 'package:flutter/material.dart';
  +import 'package:flutter/rendering.dart';
   
   class PestoDemo extends StatelessWidget {
     PestoDemo({ Key key }) : super(key: key);
  
positive.code:     fontSize: fontSize,
      fontWeight: fontWeight,
      textBaseline: TextBaseline.alphabetic,
      height: height
    );
  }
  
  
negative.code:         builder: (BuildContext context, BoxConstraints constraints) {
            final Size size = constraints.biggest;
            final double appBarHeight = size.height - statusBarHeight;
            final double extraPadding = new Tween<double>(begin: 10.0, end: 24.0).lerp(
              ((appBarHeight - kToolBarHeight) / _kAppBarHeight).clamp(0.0, 1.0)
            );
            final double logoHeight = appBarHeight - 1.5 * extraPadding;
            return new Padding(
              padding: new EdgeInsets.only(
                top: statusBarHeight + 0.5 * extraPadding,
                bottom: extraPadding
              ),
              child: new Center(
                child: new PestoLogo(showText: appBarHeight >= 70.0, height: logoHeight)
              )
            );
          }
  