text: ﻿using System;
  using System.Collections.Generic;
  using System.Threading.Tasks;
  using Windows.UI.Xaml.Navigation;
  
  namespace TODOFileHandlingSample.Mvvm
  {
      public abstract class ViewModelBase : BindableBase, Services.NavigationService.INavigatable
      {
          public virtual Task OnNavigatedToAsync(string parameter, NavigationMode mode, Dictionary<string, object> state)
          {
              return Task.FromResult<object>(null);
          }
  
          public virtual Task OnNavigatedFromAsync(Dictionary<string, object> state, bool suspending)
          {
              return Task.FromResult<object>(null);
          }
  
      }
  }