code: function mkdir(path, mode, callback) {
          if (typeof mode === "function") {
              callback = mode;
              mode = parseInt("0755", 8);
          }
          appshell.fs.makedir(path, mode, function (err) {
              if (err) {
                  callback(_mapError(err));
              } else {
                  stat(path, function (err, stat) {
                      callback(err, stat);
                  });
              }
          });
      }
docs: Create a directory at the given path, and call back asynchronously with
  either a FileSystemError string or a stats object for the newly created
  directory. The octal mode parameter is optional; if unspecified, the mode
  of the created directory is implementation dependent.
  
  @param {string} path
  @param {number=} mode The base-eight mode of the newly created directory.
  @param {function(?string, FileSystemStats=)=} callback