docs: def upsert_document_acl_trigger(plpy, td):
      """Trigger for filling in acls when legacy publishes.
  
      A compatibility trigger to upsert authorization control entries (ACEs)
      for legacy publications.
      """
      modified_state = "OK"
      uuid_ = td['new']['uuid']
      authors = td['new']['authors'] and td['new']['authors'] or []
      maintainers = td['new']['maintainers'] and td['new']['maintainers'] or []
      is_legacy_publication = td['new']['version'] is not None
  
      if not is_legacy_publication:
          return modified_state
  
      # Upsert all authors and maintainers into the ACL
      # to give them publish permission.
      permissibles = []
      permissibles.extend(authors)
      permissibles.extend(maintainers)
      permissibles = set([(uid, 'publish',) for uid in permissibles])
  
      plan = plpy.prepare("""\
  SELECT user_id, permission FROM document_acl WHERE uuid = $1""",
                          ['uuid'])
      existing_permissibles = set([(r['user_id'], r['permission'],)
                                   for r in plpy.execute(plan, (uuid_,))])
  
      new_permissibles = permissibles.difference(existing_permissibles)
  
      for uid, permission in new_permissibles:
          plan = plpy.prepare("""\
  INSERT INTO document_acl (uuid, user_id, permission)
  VALUES ($1, $2, $3)""", ['uuid', 'text', 'permission_type'])
          plpy.execute(plan, (uuid_, uid, permission,))