Dear Maintainer, Problematic lines seem to be [1][2][3]. After fixing all of them, I was able to build successfully your package in a sid chroot environment.
Kind Regards [1] https://sources.debian.org/src/ns3/3.40-1/ns-3.40/doc/models/source/conf.py/#L68 [2] https://sources.debian.org/src/ns3/3.40-1/ns-3.40/doc/manual/source/conf.py/#L68 [3] https://sources.debian.org/src/ns3/3.40-1/ns-3.40/doc/tutorial/source/conf.py/#L66