code: function hasMatchingJadeFileInPages(srcDir, url, pages, jadeOptions, callback) {
      if (typeof pages[url] === 'undefined') {
          // get the possible jade file path
          var extension = path.extname(url);
          var jadeFilePath;
          var htmlFilePath;
          if (extension === ".html" /* || extension === ".htm" */) {
              jadeFilePath = path.join(srcDir, url.substring(0, url.length - extension.length) + ".jade");
              htmlFilePath = path.join(srcDir, url);
          } else {
              jadeFilePath = path.join(srcDir, url + "/index.jade");
              htmlFilePath = path.join(srcDir, url + "/index.html");
          }
          // see if the jadefile exsists
          fs.exists(jadeFilePath, function (exsits) {
              // store the result in a new HTML page
              pages[url] = new HTMLPage({
                  matchingJadeFilePath: (exsits)?jadeFilePath:null,
                  htmlFilePath: htmlFilePath,
                  jadeOptions: jadeOptions
              });
              callback(!!pages[url].matchingJadeFilePath, pages[url]);
          });
      } else {
          callback(!!pages[url].matchingJadeFilePath, pages[url]);
      }
  }
docs: creates a jade page if it doesn't exist in cache