Im running into the issue that the browser's console is spitting the error a is undefined.
heres the snippet of code that this is occuring in.

XMLElement xml = new XMLElement(this, rest);

  // parse XML results
  XMLElement a = xml.getChild(0).getChild(0); 
  String fm = a.getStringAttribute("farm");
  String sv = a.getStringAttribute("server");
  String id  = a.getStringAttribute("id");
  String sc = a.getStringAttribute("secret");
  // build http string
  String url = "http://farm"+fm+".static.flickr.com/"+ sv + "/" + id + "_" + sc + "_z.jpg";

  return url;
};

the code runs in processing just fine...