Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Struct template result<This(Cont, It, It), void>

boost::xpressive::op::insert::result<This(Cont,It,It),void>

template<typename This, typename Cont, typename It> 
struct result<This(Cont, It, It), void> {
  // types
  typedef void type;
};