private void RemoveBt_Clicked(object sender, EventArgs e) { if (sender is Button button) { if (Visitor.Friends.Contains(Visitee)) { Visitor.Friends.Remove(Visitee); _localData.DeleteFriend(Visitor, Visitee); button.Text = AddString; } else { Visitor.Friends.Add(Visitee); _localData.AddNewFriend(Visitor, Visitee); button.Text = RemoveString; } } }