ifier">x</span></code> in the first argument
          <code class="computeroutput"><span class="identifier">result</span></code>. <code class="computeroutput"><span class="identifier">Result</span></code>
          might already contain data. In this case the intersection of <code class="computeroutput"><span class="identifier">y</span></code> and <code class="computeroutput"><span class="identifier">x</span></code>
          is <code class="computeroutput"><span class="identifier">added</span></code> the 