I swear there used to be something like this.
I'm writing a lot of Markdown with embedded code. I would like to have EMACS treat code in GitHum fenced code according to the default mode for that type of code. That is, if I write:
...and this excellent piece of code computes a function significant to number theory: ```python def even(x): return (x % 2) == 0 ```
I would like the code within the fences to be treated as Python while the code outside the fences is Markdown.