public CSharpSourceTree Execute(RazorCodeDocument document, CSharpSourceTree sourceTree)
        {
            var activeDirectives = document.GetCSharpRenderingDirectives();

            if (activeDirectives == null)
            {
                var discoveredDirectives = new List <IRazorDirective>();
                AddDiscoveredDirectives(sourceTree, discoveredDirectives);

                document.SetCSharpRenderingDirectives(discoveredDirectives);
            }

            return(sourceTree);
        }