function localProperties(prop) {
    if (prop[0] == '_') { return false; }
    if (self.__ownProperties.indexOf(prop) != -1) { return false; }
    return true;
  }
Render response.

Render `template`, defaulting to the template for the current action, with
optional `options`.  If optional callback `fn` is given, the response will
not be sent, but rather supplied to the callback.

Options:  
 - `format`  response format, defaults to `'html'`
 - `engine`  view engine, defaults to `'view engine'` setting or `'ejs'`

Examples:

    this.render();

    this.render('show');

    this.render({ format: 'xml' });

    this.render('email', function(err, body) {
      // send email with `body`
    });

@param {String} template
@param {Object} options
@param {Function} fn
@api public