turns the number
            of elements <code class="computeroutput"><span class="identifier">x</span></code> in <code class="computeroutput"><span class="identifier">rng</span></code> where <code class="computeroutput"><span class="identifier">x</span>
            <span class="special">==</span> <span class="identifier">val</span></code>
            is <code class="computeroutput"><span class="keyword">true</span></code>.
          </p>
<h6>
<a name="range.reference.algorithms.non_mutating.count.h2"></a>
