public async Task <List <AssemblyNode> > BuildAssemblyTree(Task <CciModuleSource> assembliesTask,
                                                                   bool constrainedMutation, CciMethodMatcher matcher)
        {
            var modules    = await assembliesTask;
            var assemblies = CreateNodesFromAssemblies(modules, matcher)
                             .Where(a => a.Children.Count > 0).ToList();

            var root = new CheckedNode("");

            root.Children.AddRange(assemblies);
            ExpandLoneNodes(root);

            if (assemblies.Count == 0)
            {
                throw new InvalidOperationException(UserMessages.ErrorNoFilesToMutate());
            }
            //  _reporting.LogError(UserMessages.ErrorNoFilesToMutate());
            return(assemblies);
            //Events.OnNext(assemblies);
        }