special">(</span><span class="identifier">S</span><span class="special">)</span></code>
          is enclosed by <code class="computeroutput"><span class="identifier">R</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span></code> iif
          <code class="computeroutput"><span class="special">(</span><span class="identifier">R</span><span class="special">(</span><span class="identifier">S</span><span class="special">)</span>
          <span class="identifier">i