code: function(callback) {
      crypto.randomBytes(16, function(err, buffer) {
          if (err) {
              return callback(err);
          }
  
          return callback(null, buffer.toString('base64'));
      });
  }
docs: Generate a random lock token.
  
  @param   {Function}  callback        Invoked with the token when complete
  @param   {Error}     callback.err    An error that occurred, if any
  @param   {string}    callback.token  The randomly generated token
  @api private