Infrastructure for extended formulas with multiple parts
        on the right-hand side and/or multiple responses on the
        left-hand side.
c(person(given = "Achim", family = "Zeileis", role =
c("aut", "cre"), email = "Achim.Zeileis@R-project.org"),
person(given = "Yves", family = "Croissant", role = "aut",
email = "Yves.Croissant@univ-reunion.fr"))
Achim Zeileis [aut, cre], Yves Croissant [aut]