class="function"><a name="tag-2">tag/2</a></h3>
<div class="spec">
<p><tt>tag(Key::<a href="#type-info">info()</a>, Value::<a href="#type-info">info()</a>) -&gt; <a href="#type-span">span()</a></tt><br></p>
</div><p>Add a tag to the span in the process dictionary. If the span is
  not active, a fake/empty span is returned with the default values and
  timestamp set to 0.</p>

<h3 class="function"><a name="tag-3">tag/3</a></h3>
<div class="spec">
<p><tt>tag(Key::<a href="#type-info">info()</a>, Value::<a hre