After many curse words I figured it out. A two-stage filter was needed. The 5th line solves the problem of colliding domain cookies:
NowCookie=http.cookies.SimpleCookie() # Instantiate a SimpleCookie object savedCookie=os.environ.get('HTTP_COOKIE') # get the cookie string if savedCookie: # Already is a domain cookie NowCookie.load(savedCookie) # Could be any domain cookie if CookieName in NowCookie: # Look for a specific cookie savedCookie=NowCookie[CookieName].value # Load the cookie string into a dict self.List=list(savedCookie.split('~')) # Parse the payload string delimited at tilde return self.List=[hashlib.sha1(repr(time.time()).encode()).hexdigest(), '', ''] # Else default payload self.Write() # Tell the client to remember -- Gnarlie -- http://mail.python.org/mailman/listinfo/python-list