the $sum
expression
(sum: StringAdd).self
(sum: StringFormat).self
(sum: ArrowAssoc[AggregationFramework.Sum]).x
(Since version 2.10.0) Use leftOfArrow
instead
(sum: Ensuring[AggregationFramework.Sum]).x
(Since version 2.10.0) Use resultOfEnsuring
instead
the
$sum
expression