I'm trying to remove some factors from ISAM2 (similar to #1119), and it seems that I need to track their indices using gtsame.ISAM2Result.newFactorsIndices.

Unfortunately this seems to be missing in Python:

> isam = gtsam.ISAM2()
...
> res = isam.update(graph, init_vals)
> type(res)
<class 'gtsam.gtsam.ISAM2Result'>
> print(res.newFactorsIndices)
AttributeError: 'gtsam.gtsam.ISAM2Result' object has no attribute 'newFactorsIndices'

Is there a workaround or am I doing something wrong?

Setup: gtsam 4.1.1 / Ubuntu 20.04.4 / Python 3.8