kernels not shutting down when users close tabs

[shimwell]

[shimwell]

Perhaps this should be mentioned in the intro video

[shimwell]

perhaps a solution is here https://tljh.jupyter.org/en/latest/topic/idle-culler.html

[shimwell]

Got some nice suggestions from for this issue

basically there are two problems here which can be fixed by:
Culling idle notebook servers https://tljh.jupyter.org/en/latest/topic/idle-culler.html
Closing tabs that are no longer in use https://gist.github.com/agoose77/1499db7e15788922214ca90df7b22dbf