title: Determine minimum required PHP version
body: <p>I have to find out the earliest PHP4 version my code will run under (I already know it runs on PHP5 and on PHP 4.4.9 (the last PHP4 version -- included in MAMP).</p>
  
  <p>Are there code inspection tools that will do this? Do I need to install each PHP version and see what happens :-)</p>