public MovieServiceForm()
        {
            InitializeComponent();

            foreach (Movie m in test.AllMovies())
            {
                if(!comboBox_year.Items.Contains(m.YearOfPublication))
                    comboBox_year.Items.Add(m.YearOfPublication);
            }

            foreach (Category c in test.AllCategories())
            {
                comboBox_cat.Items.Add(c.Name);
            }