text: exports.add = function (req,res,vals) {
    var sum = parseInt(vals.first) + parseInt(vals.second);
        res.writeHead(200, {'Content-Type': 'text/html'});
        res.write(`<!DOCTYPE html>
          <html>
           <head><meta charset=\"utf-8\"/>
            <title>Calculator Web Site</title>
           </head>
           <body>
             <p>The sum is:  ${String(sum)}</p>
           </body>
          </html> ` );    
        return res.end();
    };
    