title: pyspark on Google Cloud Datalab
body: <p>How does one import pyspark in google-cloud-datalab notebook?
  Even after setting up PYTHONPATH, SPARK_HOME on node, it doesn't work? Am I missing anything?</p>
  
  <pre><code>ImportErrorTraceback (most recent call last)  
    &lt;ipython-input-4-c15ae3402d12&gt; in &lt;module&gt;()
       ----&gt; 1 import pyspark
  
  ImportError: No module named pyspark
  </code></pre>