// In header: <boost/accumulators/statistics/rolling_moment.hpp>
template<int N> 
struct rolling_moment : public boost::accumulators::depends_on< rolling_window_plus1, rolling_count >
{
  // public data members
  static boost::parameter::keyword< tag::rolling_window_size > const window_size;  // tag::rolling_window::window_size named parameter 
};