core/org.jetbrains.kotlinx.dataframe.api/ensureIsColumnGroup

ensureIsColumnGroup

internal fun <C> SingleColumn<DataRow<C>>.ensureIsColumnGroup(): SingleColumn<DataRow<C>>

internal fun <C> ColumnAccessor<DataRow<C>>.ensureIsColumnGroup(): ColumnAccessor<DataRow<C>>

Checks the validity of this SingleColumn, by adding a check to see it's a ColumnGroup (so, a SingleColumn<*>) and throwing an IllegalArgumentException if it's not.