le</span></code>
          function. We use <code class="computeroutput"><span class="identifier">bind</span></code> from
          <a href="http://www.boost.org/doc/libs/release/libs/phoenix/doc/html/index.html" target="_top">Boost.Phoenix</a>
          to compose the filter from the function and the <a class="link" href="../detailed/expressions.html#log.detailed.expressions.attr" title="Generic attribute placeholder">attribute
          placeholder</a>. You can find the complete code of this example <a hr