(4) Three versions of the libretto of Lourie's The Blackamoor of Peter the Great survived: the earliest is a Russian libretto (Libl
); a modified English version (Lib2) (Irina Graham Collection, Amherst Center for Russian Culture); and the published version of the English libretto (Lib3) in Irina Graham, "Materialen zur Opera Arap Petra Velikogo/The Blackamoor of Peter the Great," in Studien zur Musik des XX.
Examples for such "library" modules are lib$$$ or libL. (Although "structural refinement" and "grouping" really refer to the same underlying idea, we prefer to use the former in the case of top- down development and the latter when constructing programs in a "bottom-up" fashion from existing parts.)
Module Main needs to refer to b from lib$$$ as well as to b exported by libL. We have no authority over the names that lib$$$ exports.