amming can continue without a compilation problem.
      Furthermore this scales better than having to constant check for nested type
      existence via BOOST_TTI_HAS_TYPE in complicated template metaprogramming code.
    </p>
<h4>
<a name="the_type_traits_introspection_library.tti_nested_type.h2"></a>
      <span class="phrase"><a name="the_type_traits_introspection_library.tti_nested_type.checking_if_the_member_type_exists"></a></span><a class="link" href="tti_nested_type.html#the_type_traits_introspecti