title: print(__doc__) in Python 3 script
body: <p>I can't figure out what does the <code>print(__doc__)</code> do at the beginning of a script, like <a href="http://scikit-learn.org/stable/auto_examples/classification/plot_digits_classification.html#example-classification-plot-digits-classification-py">in this Scikit example</a>.</p>
  
  <p>I have been looking for <strong>Python docstrings</strong> in google, and it seems <code>__doc__</code> is useful to provide some documentation in, say, functions. But I can't see what does <code>__doc__</code> do in the middle of a script.</p>