title: Array in python with arbitrary index
body: <p>I am a beginner of python.
  I want to have arrays with arbitrary index running from <code>p</code> to <code>q</code>, instead of from 0.</p>
  
  <p>How to create an array with <code>q-p+1</code> elements with index from <code>p</code> to <code>q</code>?</p>