code: function _readFile(fileName, callback) {
      fs.readFile(fileName, "utf8", function (err, data) {
          var content = "";
          if (!err) {
              content = data;
          }
          callback.apply(null, [fileName, content]);
      });
  }
docs: Extract content locally from the file system used fs.readFile()
  
  @param {String} fileName - fullpath of the document
  @param {Function} callback - callback handle to post the content back