title: How to target the first use of a template on a page with Hugo?
body: <p>I want to add an ID to the first use of a template on a page with Hugo.</p>
  
  <p>Is there some way of testing for the first use of a template on a page?</p>
  
  <p>E.g. my page has two mailing list sign-up forms, both from my 'subscribe.html' partial. I want to add <code>id="subscribe"</code> to the first instance so I can target it with a link.</p>