anchor.diff: +import 'dart:async';
  +import 'dart:convert';
  +
   import 'package:flutter/material.dart';
  -
  +import 'package:flutter/services.dart';
  +import 'package:rxdart/rxdart.dart';
   
   const double _kFlexibleSpaceMaxHeight = 180.0;
   
  
positive.code:   static final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<
        ScaffoldState>();
  
  
    List<Widget> buildItem() {
      return _kTitleColors.map((color) =>
      new Container(
        height: 150.0,
        color: color,
      )).toList();
    }
  
  
negative.code:                         gradient: const LinearGradient(
                            begin: Alignment.topCenter,
                            end: Alignment.bottomCenter,
                            stops: const [.7, 1.0],
                            colors: const <Color>[
                              const Color(0x00000000), const Color(0x60FF5722)],
                          ),
  