public void OnBackStackClickFragment()
 {
     try
     {
         if (PageNumber == 0)
         {
             if (FragmentListTab0.Count > 1)
             {
                 var currentFragment = FragmentListTab0[FragmentListTab0.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
         else if (PageNumber == 1)
         {
             if (FragmentListTab1.Count > 1)
             {
                 var currentFragment = FragmentListTab1[FragmentListTab1.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
         else if (PageNumber == 2)
         {
             if (FragmentListTab2.Count > 1)
             {
                 var currentFragment = FragmentListTab2[FragmentListTab2.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
         else if (PageNumber == 3)
         {
             if (FragmentListTab3.Count > 1)
             {
                 var currentFragment = FragmentListTab3[FragmentListTab3.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
         else if (PageNumber == 4)
         {
             if (FragmentListTab4.Count > 1)
             {
                 var currentFragment = FragmentListTab4[FragmentListTab4.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
         else if (PageNumber == 5)
         {
             if (FragmentListTab5.Count > 1)
             {
                 var currentFragment = FragmentListTab5[FragmentListTab5.Count - 1];
                 if (currentFragment != null)
                 {
                     RemoveFragment(currentFragment);
                 }
             }
             else
             {
                 Context.Finish();
             }
         }
     }
     catch (Exception e)
     {
         Console.WriteLine(e);
     }
 }