title: syntax to use a constant in parenthesis of add (new DateInterval('')) command
body: <p>I have a constant to syncronize the MYSQL server hour with my country's hour.</p>
  
  <p>in <code>add(new DateInterval('PT3H'))</code> command, <strong>instead of 3</strong> I want to use my constant.</p>
  
  <p>I ask for the correct syntax. I tried <code>{MY_CONSTANT}</code> however I got <code>Unknown or bad format error</code> message.</p>