singly_linked_list.py: psf/black (#2008)

* singly_linked_list.py: psf/black

* updating DIRECTORY.md

* Update singly_linked_list.py

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

Christian Clauss committed 5y ago

0e6e5056b3fede1705c6081543bb129b97ff4d35

Parent: 2431001

Committed by GitHub <[email protected]> on 5/19/2020, 11:54:25 AM