queue">pqueue()</a>, X2::<a href="#type-pqueue">pqueue()</a>) -&gt; <a href="#type-pqueue">pqueue()</a></tt><br></p>
</div><p>
  <h4><a name="Join_two_priority_queues.">Join two priority queues.</a></h4>
  O(N)</p>

<h3 class="function"><a name="len-1">len/1</a></h3>
<div class="spec">
<p><tt>len(X1::<a href="#type-pqueue">pqueue()</a>) -&gt; non_neg_integer()</tt><br></p>
</div><p>
  <h4><a name="Determine_the_length_of_a_priority_queue.">Determine the length of a priority queue.</a></h4>
  O(N)</p>

<h3 c