/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/ is in python-sagenb-export 3.2-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/__init__.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/asset_handler.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/export_handler.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/jinja2_env.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/list_handler.html
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/list_handler.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/start_sagenb_handler.py
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/run-sagenb.html
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/sagemath_icon.svg
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/sagenb-export.css
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/sagenb-export.js
/usr/lib/python2.7/dist-packages/sagenb_export/nbextension/www/start-sagenb.js