marked aggregateBy for removal

Author: Jolanrensen

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/aggregation/modes/aggregateBy.kt

@@ -3,12 +3,14 @@ package org.jetbrains.kotlinx.dataframe.impl.aggregation.modes
 import org.jetbrains.kotlinx.dataframe.DataFrame
 import org.jetbrains.kotlinx.dataframe.DataFrameExpression
 import org.jetbrains.kotlinx.dataframe.DataRow
+import org.jetbrains.kotlinx.dataframe.annotations.CandidateForRemoval
 import org.jetbrains.kotlinx.dataframe.api.GroupBy
 import org.jetbrains.kotlinx.dataframe.api.Grouped
 import org.jetbrains.kotlinx.dataframe.api.cast
 import org.jetbrains.kotlinx.dataframe.impl.aggregation.aggregateInternal
 import org.jetbrains.kotlinx.dataframe.impl.namedValues
 
+@CandidateForRemoval
 internal fun <T> Grouped<T>.aggregateBy(body: DataFrameExpression<T, DataRow<T>?>): DataFrame<T> {
     require(this is GroupBy<*, T>)
     val keyColumns = keys.columnNames().toSet()