construct using `Map1Column with StrColumn`
construct using `Map1Column with StrColumn`

... so no need to override isDefinedAt

quasar-analytics/quasar,quasar-analytics/quasar,slamdata/slamengine,slamdata/quasar,quasar-analytics/quasar,slamdata/slamengine,djspiewak/quasar,slamdata/slamengine,quasar-analytics/quasar