title: wordpress: display current tag-id
body: <p>With</p>
  
  <pre><code>$tag = single_tag_title('', false);
  </code></pre>
  
  <p>I can get the name of the currently chosen tag. Right?</p>
  
  <p>But how can I get also the ID of the chosen tag? "single_tag_id" does not exist. And afterwards I would like to show only posts with the tag-id.</p>
  
  <pre><code>$args = array(
              'tag' =&gt; 'ID HERE?',
          );
  </code></pre>
  
  <p>But I can not put a number into 'tag'. How can I filter with tag-id and not do it by name?</p>