Pipe a notebook to black using jupytext

[mwouts]

One can reformat a notebook with black and jupytext with, for instance,

jupytext notebook.ipynb --to py:light -o - | black - | jupytext --from py:light -o notebook.ipynb 

But this is not perfect!

Possible improvements would be

• preserve the output cells (and fix the --update flag which does not seems to work in this context)
• export to a default format ('auto:light'), and detect the text format automatically auto-detect input format #148
• remove jupytext's comment when input is taken from the stdin

[jupytext] Converting '<_io.TextIOWrapper name='<stdin>' mode='r' encoding='UTF-8'>' to 'notebook.ipynb' (destination file replaced)

• make sure Jupytext does not add too much metadata to the notebook. Especially, the transformation should not add a Jupytext entry in the metadata. Also, I would prefer not to get 'lines_to_end_of_cell_marker' metadata on code cells.

[mwouts]

Made available in version 1.0-rc.