Setting Extras to None is Confusing

[mlissner]

So...I want to allow people to do cuddled lists. So, I'm like, cool, I'll turn on the cuddled-lists extra. And to do that, I set the value to...None.

Could we make it so that the value is instead set to True? I'm finding this super confusing. Even the code-friendly extra...is set to None? What does None mean in this context? I'm not sure I get it.

[chrismcginlay]

https://github.com/trentm/python-markdown2/blob/master/lib/markdown2.py#L1863

In the underlying markdown2 library, it looks like (line 1863) the value set for cuddled-lists could be anything you like; if statement just checks for the presence of the cuddled-list key in extras dict.

[mlissner]

That's interesting and explains how we got to setting it to None. Maybe we should just update our docs to say that it needs to be set to True? But then people will be upset that setting it to False doesn't disable it. Perhaps this needs changing in Markdown2?