private void Btn_create_Click(object sender, EventArgs e)
        {
            string name    = Txt_nam_create.Text;
            string surname = Txt_sur_create.Text;

            if (Txt_phone_create.Text.Length > 8 && Txt_phone_create.Text.Length < 13)
            {
                string phone = Txt_phone_create.Text;

                api.insertWorker(name, surname, phone);

                Display();
            }
            else
            {
                MessageBox.Show("Vnesi veljavno telefonsko številko");
            }
        }