'Yields the URL querystring: "www.example.com?page=1" => "page=1"'

@property
def querystring(self):

    s = self.parts[QUERY].items()
    s = dict(((bytestring(k), bytestring((v if (v is not None) else ''))) for (k, v) in s))
    s = urllib.urlencode(s)
    return s
