from xml import sax
from StringIO import StringIO

class Handler(sax.handler.ContentHandler):

    def startElement(self, name, attrs):
        print 'attr  :', attrs.keys()[0]
        print 'value :', attrs.values()[0]

sax.parse(StringIO('<tag idx="1"/>'), Handler())
sax.parse(StringIO('<tag id="1"/>'), Handler())