Declared in <mp-units/framework/quantity.h>
template<
RepresentationOf<quantity_spec> ToRep,
UnitOf<quantity_spec> ToU,
RoundingPolicy Policy>
requires std::constructible_from<ToRep, rep> && detail::ExplicitlyCastable<unit, ToU{}, ToRep> &&
detail::ValidRoundingPolicyFor<Policy, rep, ToRep>
[[nodiscard]]
constexpr
QuantityOf<quantity_spec> auto
in(
ToU,
Policy policy) const;
The return value should not be discarded.