ate arguments is a union type, unless
      there is compiler support for <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_union</span></code>,
      or if <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_union</span></code> is specialised for the union type.
    </p>
<p>
      Finally, a word of caution for Visual C++ 6 users: if either argument is an
     