A few internet references report that etags for the same underlying resource but with different representation (xml, json ...) should have different etags. That is currently not the case. Added code to allow incorporation of representation info into the etag. By default the representation is "json", but future patches can pass the representation down and modify flow to match requested representation.

try:
    # Python 3+
    from urllib.parse import quote, unquote, urlencode, urlparse, parse_qs, \
        urlunparse
    from urllib.request import urlopen
except:
    # Python 2.5-2.7
    from urllib import quote, unquote, urlencode
    from urllib2 import urlopen
    from urlparse import urlparse, parse_qs, urlunparse