def need.period
import bend-kit-migrate@0.3.0.0/migrate.bend as Migrateimport Base
499def need.period(m: Maybe<&1, Scalar>) -> Result<&1, &1, Error, Period>:
500 match m:
501 case None{}:
502 Fail{Missing{KPeriod{}}}
503 case Some{SStr{b}}:
504 name.period(Tag.of(b))
505 case Some{s}:
506 Fail{BadField{KPeriod{}}}