title: Odd-length string error with binascii.unhexlify
body: <p>I'm trying to convert back and forth an ASCII string to its binary representation as follows.</p>
  
  <pre><code>s=chr(0)*15 + chr(0x01)
  bst = bin(int(binascii.hexlify(s), 16))
  n = int(bst, 2)
  binascii.unhexlify('%x' % n) 
  </code></pre>
  
  <p>However, I get the following error at the end which doesn't make much sense to me.</p>
  
  <blockquote>
    <p>1 binascii.unhexlify('%x' % n)</p>
    
    <p>TypeError: Odd-length string</p>
  </blockquote>
  
  <p>What's the issue and how can I solve it ?</p>