pelican-plugins/test_data/themes/notmyidea/templates/twitter.html

{% if TWITTER_USERNAME %}
<a href="http://twitter.com/share" class="twitter-share-button" data-count="horizontal" data-via="{{TWITTER_USERNAME}}">Tweet</a><script type="text/javascript" src="http://platform.twitter.com/widgets.js"></script>
{% endif %}