title: Coursera jupyterNotebook: revert to the beginning
body: <p>I'm using jupyterNotebook from Coursera but see no way to revert everything to the beginning.</p>
  
  <p><a href="https://i.stack.imgur.com/prnmh.png" rel="noreferrer"><img src="https://i.stack.imgur.com/prnmh.png" alt="enter image description here"></a></p>
  
  <p>The only option relevant seems to be "Revert to Checkpoint" -- but I didn't save a checkpoint at the beginning.</p>
  
  <p>Does it mean that I am unable to revert to it?</p>