* (2) Erasure by key objects */</span>   <span class="identifier">T</span><span class="special">\</span><span class="identifier">P</span><span class="special">|</span> <span class="identifier">e</span> <span class="identifier">b</span> <span class="identifier">s</span> <span class="identifier">m</span>            <span class="identifier">T</span><span class="special">\</span><span class="identifier">P</span><span class="special">|</span> <span class="identifier">e</span> <span class="identifier">i</span> <s