Use key_name instead of link_id
Some entities do not have a link_id, but all entities are guaranteed
to have a key_name (or an id).
#!/usr/bin/env python
"""
Daily cleanup job.
Can be run as a cronjob to clean out old data from the database (only expired
sessions at the moment).
"""
from django.core import management
if __name__ == "__main__":
management.call_command('cleanup')