...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::yap::operator!=
// In header: <boost/yap/expression.hpp> template<typename LExpr, typename RExpr> constexpr auto operator!=(LExpr && lhs, RExpr && rhs);