  <span class="bold"><strong>Semantics</strong></span>: The type returned by dereferencing
            an iterator to the first element in <code class="computeroutput"><span class="identifier">Seq</span></code>.
            Equivalent to <code class="computeroutput"><a class="link" href="../../../iterator/metafunctions/deref.html" title="deref"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">deref</span></code></a><span class="spe