n using this
          facility: Python will automatically create an iterator type for you (see
          <a href="http://www.python.org/doc/current/lib/built-in-funcs.html#l2h-35" target="_top"><code class="computeroutput"><span class="identifier">iter</span><span class="special">()</span></code></a>),
          and each access can be range-checked, leaving no possiblity of accessing
          through an invalidated C++ iterator.
        </p>
</div>
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