...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::histogram::axis::traits::rank — Return axis rank (how many arguments it processes).
// In header: <boost/histogram/axis/traits.hpp> template<typename Axis> constexpr unsigned int rank(const Axis & axis);