anchor.diff:        this.name, this.function, this.concurrencyMode, this.condition);
   
     @override
  -  Future process(Project project,
  +  Future<T> process(Project project,
         {Iterable<Project> dependencies: const []}) async {
       final taskDescription = '$name for project ${project.name}';
       if (!condition()) {
  
positive.code:       throw new ArgumentError('Invalid function passed into process');
      }
  
      final Callable callable = () => (function is ProjectWithDependenciesFunction
          ? function(project, dependencies)
          : function(project));
  
  
negative.code:   }
  }
  
  class _DefaultCommand<T> implements ProjectCommand<T> {
    final String name;
    final Function function;
    final CommandConcurrencyMode concurrencyMode;
  