anchor.diff:  import 'package:purity/purity.dart';
   import 'package:purity/local.dart' as local;
   import 'dart:async';
  -import 'dart:math';
  +import 'dart:mirrors';
   
   void runEndToEndTests(){
   
  
positive.code:     source.doStuff(x);
    }
  
    void callSourceMethod(){
  
    }
  }
  
  
negative.code:     setUp(_setUp);
      tearDown(_tearDown);
  
      test('A consumer can make calls to its source by proxy and receive events back by proxy', (){
        var pi = 3.142;
        executeWhenReadyOrTimeout(() => currentTestConsumer != null, () => currentTestConsumer.doStuff(pi));
        expectAsyncWithReadyCheckAndTimeout(
  