getPermissibleRateUnits method
Gets a set of permissible RateUnit
values.
A format instance does not necessarily support all RateUnit
values. It may support only a subset thereof,
thereby giving the caller control over what units to use when formatting values.
Note that this method is only relevant to rate-based inputs. In other cases, the implementation can simply return an empty set.
Implementation
@override
Set<RateUnit> getPermissibleRateUnits() => permissibleRateUnits;