/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/ is in calendarserver 5.2+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/__init__.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/delivery.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/dkim.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/localservers.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/remoteservers.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/resource.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/scheduler.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/__init__.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_delivery.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_dkim.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_localservers.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_remoteservers.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_resource.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/test/test_utils.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/utils.py
/usr/lib/python2.7/dist-packages/txdav/caldav/datastore/scheduling/ischedule/xml.py