(secondaryPrefered: StringAdd).self
(secondaryPrefered: StringFormat).self
(secondaryPrefered: ArrowAssoc[SecondaryPrefered]).x
(Since version 2.10.0) Use leftOfArrow
instead
(secondaryPrefered: Ensuring[SecondaryPrefered]).x
(Since version 2.10.0) Use resultOfEnsuring
instead
Read from any secondary, or from the primary if they are not available.