wer_typeof_helper&lt;unit&lt; Dim, System &gt;, static_rational&lt; N, D &gt;&gt;">power_typeof_helper</a><span class="special">&lt;</span><span class="identifier">unit</span><span class="special">&lt;</span> <span class="identifier">Dim</span><span class="special">,</span> <span class="identifier">System</span> <span class="special">&gt;</span><span class="special">,</span> <span class="identifier">static_rational</span><span class="special">&lt;</span> <span class="identifier">N</span><span class="special