The FIRST set for this parser, or the empty set if the production goes to \epsilon.
(mappedParser: StringAdd).+(other)
(mappedParser: StringAdd).self
(mappedParser: StringFormat).self
(mappedParser: ArrowAssoc[MappedParser[A, B]]).x
(Since version 2.10.0) Use leftOfArrow
instead
(mappedParser: Ensuring[MappedParser[A, B]]).x
(Since version 2.10.0) Use resultOfEnsuring
instead