    in the implementation of the user-defined macro might provide the best syntax
      for the caller. For example, this is the case for <code class="computeroutput"><span class="identifier">BOOST_MPL_ASSERT</span></code>
      because the majority of template meta-programming expressions contain unwrapped
      commas so it is less confusing for the user to always specify the extra parenthesis
      <code class="computeroutput"><span class="special">((...))</span></code> instead of using <code class="comp