http://tehbemfqolualhxwkyimu3bdob5s4hkrfuwbwxzbblncjy2j2owgolqd.onion/documentation.html
If the completer should not be used in this case, it
should return None or an empty set, which will cause tako to move on and
try to use the next completer. If a completer raises StopIteration ,
then following completers will not be tested, and an empty set of results will be returned.