title: python get docstring from terminal using option
body: <p>Let us say I have a file</p>
  
  <p>myfile.py</p>
  
  <pre><code>"""
  long documentation of myfile.py
  ...
  """
  
  # tons of stuf
  # this include some functions and their documentation
  </code></pre>
  
  <p>and I would like to do</p>
  
  <pre><code>bash $ python myfile.py -h
  </code></pre>
  
  <p>such that it displays all the documentation but does not execute the <code>tons of stuff</code>. (I don't care if the option is <code>--help</code> instead of <code>-h</code>.)</p>
  
  <p>I am pretty sure I have already seen it somewhere but I can't find it. Is it related to <a href="https://stackoverflow.com/questions/34689279/parsing-argument-in-python">this question</a> and to <a href="https://stackoverflow.com/questions/7123660/python-help-function-printing-docstrings">this second question</a>?</p>