mp_units::quantity_point::in

template<
    RepresentationOf<quantity_spec> ToRep,
    /* implementation-defined */ ToU>
requires detail::ValuePreservingConstruction<ToRep, rep> &&
             detail::ValuePreservingConversion<unit, rep, ToU{}, ToRep>
[[nodiscard]]
constexpr
QuantityPointOf<quantity_spec> auto
in(ToU) const;