How to use the function `pj_geodetic_to_geocentric` in boost library?

In boost/geometry/srs/projections/impl/pj_transform.hpp, Ifound a function pj_geodetic_to_geocentric, the function declaration is blow:

template <typename T, typename Range>
inline int pj_geocentric_to_geodetic( T const& a, T const& es,
                                      Range & range );
template <typename T, typename Range>
inline int pj_geodetic_to_geocentric( T const& a, T const& es,
                                      Range & range );

the function is manually converted from PROJ4, I am confused, how to use the function? the variable Range &range, how to pass a variable in the function?

I do not know how to use it!! help me please!