anchor.diff:  
       startClient(clientBuilderConfig);
       return;
  +  } else {
  +    print("You must provide a value for 'clientConfig'.");
  +    _printUsage(parser);
     }
  -
  -  String dartSdk;
  -  if (results['sdk'] == null) {
  -    print("You must provide a value for 'sdk'.");
  -    _printUsage(parser);
  -    return;
  -  } else {
  -    dartSdk = results['sdk'];
  -  }
  -
  -  String configPath;
  -  if (results['config'] == null) {
  -    print("You must provide a value for 'config'.");
  -    _printUsage(parser);
  -    return;
  -  } else {
  -    configPath = results['config'];
  -  }
  -
  -  String package = results['package'];
  -  Version version = new Version.parse(results['version']);
  -  _initClient(dartSdk, configPath, package, version);
  -  return;
   }
   
   void startClient(ClientBuilderConfig clientBuilderConfig) {
  
positive.code:   print('where <options> is one or more of:');
    print(parser.getUsage().replaceAll('\n\n', '\n'));
    exit(1);
  }
negative.code:   });
  }
  
  // TODO(adam): move to carte_de_jour.dart
  void buildVersion(String packageName,
                   Version version, ClientBuilderConfig clientBuilderConfig) {
    Logger.root.info("Starting build of ${packageName} ${version}");
  