json you can paste into jupyter notebook's code prettify configuration that makes it use black to reformat your code instead of yapf.

black_code_prettify.json

{
  "python": {
    "library": "import json\ndef black_reformat(cell_text):\n    import black\n    import re\n    cell_text = re.sub('^%', '#%#', cell_text, flags=re.M)\n    try:\n        reformated_text = black.format_str(cell_text, 88)\n    except TypeError:\n        reformated_text = black.format_str(cell_text, mode=black.FileMode(line_length=88))\n    return re.sub('^#%#', '%', reformated_text, flags=re.M)",
    "prefix": "print(json.dumps(black_reformat(u",
    "postfix": ")))"
  },
  "r": {
    "library": "library(formatR)\nlibrary(jsonlite)",
    "prefix": "cat(toJSON(paste(tidy_source(text=",
    "postfix": ", output=FALSE)[['text.tidy']], collapse='\n')))"
  },
  "javascript": {
    "library": "jsbeautify = require('js-beautify')",
    "prefix": "console.log(JSON.stringify(jsbeautify.js_beautify(",
    "postfix": ")));"
  }
}

This is neat! I created a PR to use black by default, see: ipython-contrib/jupyter_contrib_nbextensions#1452