title: Why are underscores better than hyphens for file names?
body: <p>From <a href="http://homepage.mac.com/s_lott/books/python/BuildingSkillsinPython.pdf" rel="nofollow noreferrer">Building Skills in Python</a>:</p>
  <blockquote>
  <p>A file name like <code>exercise_1.py</code> is better than the name <code>exercise-1.py</code>. We can run both programs equally well from the command line, but the name with the hyphen limits our ability to write larger and more sophisticated programs.</p>
  </blockquote>
  <p>Why is this?</p>