anchor.diff:  , pyyaml
   , nbformat
   , nbconvert
  +, nbclient
   , six
   , tqdm
   , jupyter_client
  
positive.code:     pyyaml
      nbformat
      nbconvert
      six
      tqdm
      jupyter_client
      requests
      entrypoints
      tenacity
    ] ++ lib.optionals isPy27 [
      futures
      backports_tempfile
  
negative.code: , entrypoints
  , tenacity
  , futures
  , black
  , backports_tempfile
  , isPy27
  , pytest
  