circular_linked_list: Add more len() tests (#2051)

* circular_linked_list: Add more len() tests

* fixup! Format Python code with psf/black push

* prepend()

* updating DIRECTORY.md

* Fix decrementation of self.length

* Add empty list tests

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

Christian Clauss committed 5y ago

1e8fe8efcfc499c85079659708f4afefe92ec66b

Parent: 3357768

Committed by GitHub <noreply@github.com> on 5/31/2020, 7:36:57 AM