public void Add(PatientsList list)
 {
     foreach (var i in list.Patients)
     {
         var child = new TreeViewModel();
         child.Title = "Patient";     // Level2 node name
         child.Add(i);
         Children.Add(child);
     }
 }
    private void LoadData()
    {
        var list1 = new PatientsList();

        list1.Patients.Add(new Patient {
            ID = 44, Name = "Ben Garsia", Year = 1985
        });
        list1.Patients.Add(new Patient {
            ID = 22, Name = "Melisa Mayer", Year = 1968
        });
        list1.Patients.Add(new Patient {
            ID = 33, Name = "Morgan Smith", Year = 1979
        });

        var root = new TreeViewModel();

        root.Add(list1);
        Tree.Add(root);
    }