rom being a good solution.
      </p>
<p>
        Option 2 is correct. We start thinking books as entries in a table. So it
        makes sense to start using Boost.MultiIndex. We can then add the year of
        publication, the price, etc... and we can index this new items too. So Boost.MultiIndex
        is a sound solution for our problem.
      </p>
<p>
        The thing is that there are cases where we want to maintain bimap semantics
        (use <code class="computeroutput"><span class="identifier">