title: difference between find and index
body: <p>I am new to python and cannot quite understand the difference between find and index. </p>
  
  <pre><code>&gt;&gt;&gt; line
  'hi, this is ABC oh my god!!'
  &gt;&gt;&gt; line.find("o")
  16
  &gt;&gt;&gt; line.index("o")
  16
  </code></pre>
  
  <p>They always return the same result.
  Thanks!!</p>