n class="identifier">do_copy</span></code> that performs a "slow but safe"
      copy. The last parameter passed to this function may be either a <code class="computeroutput"><a class="link" href="reference/integral_constant.html" title="integral_constant">true_type</a></code>
      or a <code class="computeroutput"><a class="link" href="reference/integral_constant.html" title="integral_constant">false_type</a></code>.
      Following that there is an overload of do_copy that uses <code class="computeroutpu