indexOfAggregationResultSingleSequence
abstract fun indexOfAggregationResultSingleSequence(values: Sequence<Value?>, valueType: ValueType): Int
Function that can give the index of the aggregation result in the input values, if it applies. This is used for AggregatorAggregationHandlers where Value== Return, and where the result exists in the input.
Like for SelectingAggregationHandler.
Defaults to -1.