// In header: <boost/icl/functors.hpp>
template<typename Combiner> 
struct version : public boost::icl::conversion< Combiner > {
  // types
  typedef version< Combiner >      type;         
  typedef conversion< Combiner >   base_type;    
  typedef base_type::argument_type argument_type;
  // public member functions
  argument_type operator()(const argument_type &);
};