How to modify appearance of comments_popup_link

index.php

<?php wp_link_pages(); ?>
|
<?php comments_popup_link(__('Comments (0)'), __('Comments (1)'), __('Comments (%)')); ?>
</div>
that would do the job – code from a default index.php

Thanks, but it appears that this page cuts out a bit of the code I posted — my problem is to get a vertical bar “|” out of the comment link. Somehow I’ve managed to get the bar to appear within the comment link, like this:
| Kommentarer (1)
I’d like it to look like:
| Kommentarer (1)
But the vertical bar is not in index.php in the first place, so the appearance of the comment link must be in some other file, and my question thus is: Which one?