title: reference to element in boost.fusion vector
body: <p><strong>EDIT - please ignore - the question resolved around a simple typo. I need a break.</strong></p>
  
  <p>How do I access a reference to an element of a boost fusion vector?</p>
  
  <p>Unlike boost.tuples's <code>tuples::get&lt;i&gt;(variable)</code> (returns a reference), the <code>fusion::at_c&lt;i&gt;(variable)</code> returns a constant and this causing me difficulties.</p>
  
  <p>The following illustrates my problem</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;boost/tuple/tuple.hpp&gt; 
  #include &lt;boost/fusion/include/vector.hpp&gt;
  #include &lt;boost/fusion/include/at.hpp&gt;
  
  using namespace boost;
  int
  main  (int ac, char **av)
  {
     fusion::vector&lt;int, char, std::string&gt; vec(1, 'x', "howdy");
     tuples::tuple &lt;int, char, std::string&gt; tup(1, 'x', "howdy");
     std::cout&lt;&lt; fusion::at_c&lt;0&gt;(vec)&lt;&lt;std::endl;  //outputs 1
     std::cout&lt;&lt; tuples::get&lt;0&gt; (tup) &lt;&lt;std::endl; //outputs 1
     //fusion::at&lt;0&gt;(vec) = 2; //doesn't compile
     tuples::get&lt;0&gt;(tup) = 2;    //works fine
     std::cout&lt;&lt; fusion::at_c&lt;0&gt;(vec) &lt;&lt;std::endl; //can't make this output 2.
     std::cout&lt;&lt; tuples::get&lt;0&gt; (tup) &lt;&lt;std::endl; //outputs 2
  
  }
  </code></pre>