- """Implement bool(Tags) check that can be repeatedly used
-
- If __nonzero__ is not implemented, "if Tags()"
- will implicitly call __len__, using up our iterator, so it is
- important that this function is defined.
+ '''
+ Implement truth value testing. If __nonzero__ is not
+ implemented, the python runtime would fall back to `len(..) >
+ 0` thus exhausting the iterator.