title: OCaml: Pad List with Zeros using Folding
body: <p>I've been stuck on this for hours now - wondering if anyone could help me out.</p>
  
  <p>I have two Lists of different lengths, and I want to pad the shorter list with 0's so that the two lists have the same length. </p>
  
  <p>I want to do this using the Folding functions, and NOT using recursion.</p>
  
  <p>Any hints are very appreciated!</p>