elementtree.ElementTree

from google.appengine.api import urlfetch
from elementtree.ElementTree import *

url="http://api.flickr.com/services/rest/"
url += "?method=flickr.photos.search&text=test"
url += "&api_key=XXX"
url += "&per_page=3"
result = urlfetch.fetch(url)
#print result.content

tree = ElementTree(fromstring(result.content))

for item in tree.findall('.//photos'):
 print item[0].get('id')
 print item[0].get('title')
for d in item:
 print d.get('title')

http://python.matrix.jp/modules/ElementTree.html

There's no need to install anything, ElementTree is included in
Python 2.5

http://docs.python.org/lib/module-xml.etree.ElementTree.html