title: Prevent jupyter notebook to run all cells on open
body: <p>I'm using Jupyter notebook to write my code, but I'm facing a problem
  that each time I open the notebook I find that all the cells are run.</p>
  <p>This causes problems when I want to add some new cells in between.</p>
  <p>So I am obliged to rerun the code from the beginning to get the right results.</p>
  <p>Is there a way I can start from where I stopped running to save time? Especially since my code takes around 4 hours to run.</p>