>set_expr<span class="emphasis"><em>N</em></span></code>.
        The value type (that is the type returned by <a class="link" href="../iterator/metafunctions/value_of.html" title="value_of"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_of</span></code></a>, <a class="link" href="../iterator/metafunctions/value_of_data.html" title="value_of_data"><code class="computeroutput"><span class="identifier">result_of</span><span c