iterated over is changed during the iteration, the
behavior is unspecified.</p>
<p>The <code>Iterator</code> is initially positioned before the first element.
Before accessing the first element the iterator must thus be advanced using
<a href="dart-core/Iterator/moveNext.html">moveNext</a> to point to the first element.
If no element is left, then <a href="dart-core/Iterator/moveNext.html">moveNext</a> returns false, <a href="dart-core/Iterator/current.html">current</a>
returns <code>null</code>, and all fu