title: os.environ doesn't show all environmental variables in Jupyter notebook
body: <p>I am finding that the following code prints out my expected environmental variable when I execute the script in a shell:</p>
  
  <pre><code>import os
  print(os.environ['STUFF'])
  </code></pre>
  
  <p>However, when I run this same code in Jupyter Notebook, I get a key error. I have tried restarting the Jupyter server. What else should I do?</p>