>Iterator1</code> is picked if there is such an element,
  otherwise the element from <code>Iterator2</code> is picked, and the other is  
deleted.</p>
 
  The first element of each iterator will be evaluated.</p>

<h3 class="function"><a name="unfold-2">unfold/2</a></h3>
<div class="spec">
<p><tt>unfold(Fun, Acc0) -&gt; Iterator</tt>
<ul class="definitions"><li><tt>Fun = <a href="#type-unfold">unfold</a>(Elem, AccIn::Acc0 | AccOut, AccOut)</tt></li><li><tt>Acc0 = <a href="#type-accumulator">accumulator()</