title: Python str object does not support item assignment when replacing array values
body: <p>It gives me an error when I try to replace part of the data.<br>
  I wanted to replace the hex value of a part of the data before it is sent back.<br>
  How should I approach this?</p>
  
  <pre><code>data, addr = s.recvfrom(32768)
  if knownClient is None:
      knownClient = addr
  if addr == knownClient:
      s.sendto(data, knownServer)
      print "Sent     : " + ":".join("{0:02X}".format(ord(c)) for c in data)
  else:
      data[10] = 0xFF #error_here
      data[11] = 0x0A #error_here
      s.sendto(data, knownClient)
  </code></pre>