code: function maybeMkdir(path, opts, callback) {
    if (typeof opts === 'function') {
      callback = opts;
      opts = null;
    }
  
    fs.exists(path, function(exists) {
      if (opts && opts.purge) {
        rimraf.sync(path);
      } else {
        if (exists) {
          return callback && callback();
        }
      }
  
      (function tryMkdir() {
        fs.mkdir(path, function(err) {
          if (err) {
            // TODO(gaye): Eventually we should give up.
            debug('error maybeMkdir, will try again ' + path + ': ' + err);
            return tryMkdir();
          }
  
          return callback(null);
        });
      })();
    });
  }
docs: Make the directory if it doesn't exist.
  
  @param {string} path to directory.
  @param {Object} opts optional args.
  purge (boolean) - whether or not to purge existing files.
  @param {Function} callback invoke when done.