Bookstore.BookSearcher.BookSearcherUI.GetIsbn C# (CSharp) Method

        static string GetIsbn(XmlDocument queryDocument)
        {
            string xpathQueryForIsbn = "/query/isbn";
            XmlNode isbnNode = queryDocument.SelectSingleNode(xpathQueryForIsbn);
            string isbn = null;
            if (isbnNode != null)
            {
                isbn = isbnNode.InnerXml.Trim();
            }

            return isbn;
        }