anchor.diff:  
   import 'dart:async';
   import 'package:mongo_dart/mongo_dart.dart';
  -import 'package:rpc/rpc.dart';
   
   class Result {
     String result;
  
positive.code: 
  /// Expose the NOAA daily temperatures as a web service
  ///
  @ApiClass(name:'noaa', version: 'v1')
  class ApiTemperatureNoaa {
    Db db;
    DbCollection coll;
  
negative.code:     coll = db.collection('daily');
    }
  
    /// Get the daily historical min/max temperatures for a
    /// given station GHCND identifier.
    /// http://localhost:8080/noaa/v1/ghcnd/USW00014739
    /// Return a list of strings
    /// [[19800101,26,38], [19800102,26,37], ...]
    // @ApiMethod(path: 'ghcnd/{ghcnd}')
    Future<List<List<String>>> getTemperature(String ghcnd) async {
      //String ghcnd = 'USW00014739';
      List pipeline = [];
  