private void ContributeButton_Click(object sender, EventArgs e)
{
var result = MessageBox.Show("Do you wish to contribute this book?", "Loan",
MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (result == DialogResult.Yes)
{
bll.addBook(BookNameTb.Text, BookYearTb.Text, BookSummaryTb.Text, BookSubjectCb.Text);
}
}