This brings back memories. I used to work at Cisco in the early 2000s.

Unlike many of the places I worked at since, Cisco (atleast the BU where I worked at) had a dedicated team to implement the libraries and tools needed to script/automate the routers via the consoles. It was a library based on TCL/Expect that connected directly to the command line to get things done. It had a core library maintained by the team and an extensions directory that had modules developed by separate teams for their own features. Finally, there was a regression suite that tested complex setups to make sure that everything was performing well. It also had routines to connect to traffic generators. The one we used was from a company called Ixia. The whole thing had regular release cycles and was treated as a first class internal product rather than just a script someone had written. As part of the work I needed to do, I even wrote a little Emacs mode to handle IOS config files https://github.com/nibrahim/IOS-config-mode

I thought this was the standard way of doing things but several of the companies I worked in since didn't have this polished an infrastructure team and it showed.

I don't know if was because of lack of adoption of TCL but several years later (2017 or so), they moved a lot of the tooling from TCL to Python and I actually went back to deliver some trainings to reskill the engineers on the new technologies.