title: Add string if length of existing string is 4
body: <p>I'd need a VBA script that reads a column of strings.
  In this column, there will be strings such as:
  ['239222', '292291', '939328', '2343', '923219', '3928']
  However, I want to add four leading zeros every time a string has a length equals to 4.</p>
  
  <p>I'd get:
  ['239222', '292291', '939328', '00002343', '923219', '00003928']</p>
  
  <p>is this possible?</p>