docs: def next(cls):
          """Return next available record identifier."""
          try:
              with db.session.begin_nested():
                  obj = cls()
                  db.session.add(obj)
          except IntegrityError:  # pragma: no cover
              with db.session.begin_nested():
                  # Someone has likely modified the table without using the
                  # models API. Let's fix the problem.
                  cls._set_sequence(cls.max())
                  obj = cls()
                  db.session.add(obj)
          return obj.recid