ation occurs over values in index order. Changing
the values does not affect iteration, but changing the valid
indices—that is, changing the list's length—between iteration
steps causes a <a href="dart-core/ConcurrentModificationError-class.html">ConcurrentModificationError</a>. This means that only growable
lists can throw ConcurrentModificationError. If the length changes
temporarily and is restored before continuing the iteration, the iterator
does not detect it.</p>
<p>It is generally not allowed to