ppear</span>, <span class="nv">zero</span> <span class="nv">returned</span>

 <span class="o">!</span> <span class="nv">a</span> <span class="nv">numeric</span> <span class="nv">value</span> <span class="nv">is</span> <span class="nv">returned</span>,
 <span class="o">!</span> <span class="nv">so</span> <span class="nv">it</span> <span class="nv">can</span> <span class="nv">be</span> <span class="nv">used</span> <span class="nv">in</span> <span class="nv">numeric</span> <span class="nv">expression</span>
 <