s="comment">// Print the abstract of this book</span>
<span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">map_by</span><span class="special">&lt;</span><span class="identifier">author</span><span class="special">&gt;::</span><span class="identifier">iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">bm</span><span class="special">.</span><span class="identifier">by</span><span class="special">&lt;</span><span c