title: How to create a new tuple type from an old one and a type in boost?
body: <p>I have a tuple type. I want to add a element type in it to get a new tuple type. I can do it like</p>
  
  <pre><code>decltype tuple_cat(MyTuple, std::tuple&lt;MyType&gt;())
  </code></pre>
  
  <p>However, I don't find <code>tuple_cat</code> in <code>boost::tuple</code>, how to do it in boost?</p>