boost::gil::Point2DConcept

template<typename P>
struct Point2DConcept;

concept Point2DConcept<typename T> : PointNDConcept<T>
{
    where num_dimensions == 2;
    where SameType<axis<0>::type, axis<1>::type>;

    typename value_type = axis<0>::type;

    value_type const& operator[](T const&, size_t i);
    value_type& operator[](T&, size_t i);

    value_type x,y;
};