support jupytext py:percent flavor cell magic

[fecet]

Jupytext suggest writing cell magic in such format:

# %%
# %%time

so this is a rough implementation, but it seems to be working well.

[kiyoon]

I think you need to do

line.strip() == "# %%"

same for lua

Because some line can unfortunately end with that format randomly

[fecet]

is vim.fn.trim the lua version of str.strip?

[kiyoon]

Sounds like so, but need to confirm its behaviour

[kiyoon]

Thank you so much!