title: Hidden code cells (Jupyter lab) show up on github
body: <p>Jupyter Lab allows the user to hide a code cell, hide an output cell, or both. This is a very nice feature that is saved when saving the notebook, so it remembers to hide the cells when re-opening the notebooks.</p>
  <p>When such notebooks are uploaded on Github, and the notebook is viewed on Github, the hidden cells are not anymore hidden.</p>
  <p>Is there a workaround or do we have to wait for the Github wizards to implement this feature?</p>