 iterators will never  
return.</p>
 
  If duplicate <code>Key</code>s are present in the iterator it is undefined
  which will appear in the final map.</p>

<h3 class="function"><a name="ukeymerge-3">ukeymerge/3</a></h3>
<div class="spec">
<p><tt>ukeymerge(N, TupleIterator1, TupleIterator2) -&gt; TupleIterator3</tt>
<ul class="definitions"><li><tt>N = pos_integer()</tt></li><li><tt>TupleIterator1 = <a href="#type-iterator">iterator</a>(Elem1)</tt></li><li><tt>TupleIterator2 = <a href="#type-iterator">itera