code: function (rep, callback) {
                  if (_.isFunction(config.prepare)) {
                      config.prepare(rep, wrap(callback));
                  } else {
                      callback(null, rep);
                  }
              }
docs: Looks for an asynchronous prepare method for programmatic configuration of the outbound hal entity. As with
  toHal(), the prepare method can modify the existing rep or create an entirely new one.
  @param rep
  @param callback