boost::gil::PointNDConcept

template<typename P>
struct PointNDConcept;

concept PointNDConcept<typename T> : Regular<T>
{
    // the type of a coordinate along each axis
    template <size_t K>
    struct axis; where Metafunction<axis>;

    const size_t num_dimensions;

    // accessor/modifier of the value of each axis.

    template <size_t K>
    typename axis<K>::type const& T::axis_value() const;

    template <size_t K>
    typename axis<K>::type& T::axis_value();
};