 same associated types (<code class="computeroutput"><span class="identifier">value_type</span></code>, <code class="computeroutput"><span class="identifier">reference</span></code>,
          <code class="computeroutput"><span class="identifier">pointer</span></code>, and <code class="computeroutput"><span class="identifier">difference_type</span></code>). Second, even some of
          the core functionality is the same: <code class="computeroutput"><span class="keyword">operator</span><span class="specia