Add skip-execution cell tag functionality

[chrisjsewell]

This is something that has been requested and up-voted in jupyter-book/jupyter-book#833

I guess this is the simplest implementation, although happy to discuss (a) if you would back this idea in the first place and (b) is you think any more configuration is needed (e.g. at the traitlets level)

[chrisjsewell]

I guess this is also related to https://discourse.jupyter.org/t/is-there-a-cell-tag-convention-to-skip-execution/5445, but nothing really come of that, so I wanted to be a bit more direct 😬

I guess you could add a traitlets options, which disabled this feature by default; so it is not a potentially breaking change for anyone else, but allowed us folks that want do want to have such functionality to use it (acknowledging the disclaimer that it is maybe a "bad" practice).

[davidbrochart]

I think it can be useful, but maybe we could make it more generic? For instance, if we decide to make it configurable through a trait, we could have one such as skip_cells_with_tag=skip-execution, what do you think?

[chrisjsewell]

we could have one such as skip_cells_with_tag=skip-execution, what do you think?

that works for me cheers 😄 will update the PR in a bit...

[chrisjsewell]

Hey @davidbrochart I have updated the PR with the skip_cells_with_tag trait

[chrisjsewell]

oops fixed flake8 (fancy me adding a pre-commit config for that and maybe black, and mypy?)

[davidbrochart]

fancy me adding a pre-commit config for that and maybe mypy?

Sure, thanks.

[chrisjsewell]

Sure, thanks.

I'll do that in another PR ta

[davidbrochart]

@takluyver we are seeing the same error as in #159 (zmq.error.ZMQError: Address already in use).

[davidbrochart]

Awesome, thanks!