public static void SetEnum2D <T>(this Grasshopper.Kernel.IGH_DataAccess DA, int index, IEnumerable <IEnumerable <T> > data)
{
var tree = new DataTree <T>();
var basePath = DA.ParameterTargetPath(index);
foreach (var entry in data.Select((o, i) => new { Index = i, Item = o }))
{
var path = basePath.AppendElement(entry.Index);
tree.AddRange(entry.Item, path);
}
DA.SetDataTree(index, tree);
}