ReadonlydirReadonlyoptionsOptionalselectIn addition to matching exact values,
numerical values may also match keys with the same plural rule category,
i.e. one of zero, one, two, few, many, and other.
Different languages use different subset of plural rule categories.
For example, cardinal English plurals only use one and other,
so a key zero will never be matched for that locale.
OptionaltoOptionaltoReadonlytype
The resolved value of a :currency, :integer, :number, :offset, or :unit expression.