public void SetModel(Model model)
{
this.model = model;
BackToList = new MvvmCommand(() => PageManager.ChangePageTo(PageType.StudentList), () => true);
Agree = new MvvmCommand(() => model.SetOnDuty(FirstStudent, SecondStudent), () => true);
}
void PageManager_CurrentPageChanged(object sender, PageType e)
{
CurrentPage = PageManager.GetPageByType(e);
NotifyPropertyChanged("CurrentPage");
}