title: Meaning of index [i:i + 16] notation?
body: <pre><code>def hexdump(text, encoding='utf-8'):
      text_bytes = text.encode(encoding)
      for i in range(0, len(text_bytes), 16):
          chunk = text_bytes[i:i + 16]
  </code></pre>
  <p>What is <code>text_bytes[i:i + 16]</code> exactly doing?</p>