title: Print a string as hexadecimal bytes
body: <p>I have this string: <code>Hello, World!</code> and I want to print it using Python as '48:65:6c:6c:6f:2c:20:57:6f:72:6c:64:21'.</p>
  <p><code>hex()</code> works only for integers.</p>
  <p>How can it be done?</p>