How do I echo categories with an if statement and display php inside of the IF?

I am having issues displaying tags only if there is tags and including php inside of it as well. This is what I tried but nothing is showing.

  <?php
  if( has_tag() ) { ?>



                      <!-- Start of tags -->

                            <?php echo get_the_term_list( $post->ID, 'download_tag', 'Tags ', ', ', '' ); ?>

                  <!-- End of tags  -->

 <?php
    }
   ?>