title: Generate customer ID's with Python 2.7
body: <p>In the program I am writing I need to generate a customer ID for every new client that gets registered into the system.</p>
  
  <p>I want the list to start at 0001 and each new client ID is the next consecutive number from the last one registered (for example if the last registered client ID is 0234 the new registered ID needs to be 0235).</p>