Any code loaded from SourceFiles is saved into File in PO format.
A file specification or a list of file specifications;
A file specification, ‘.po’ extension optional.
Any module declarations, predicates, multifile
clauses, or directives encountered in SourceFiles are
saved in object format into the file denoted by File. Source
file information as provided by
source_file/[1,2] for the
relevant predicates and modules is also saved.
File can later be loaded by
load_files/[1,2], at which
time any saved directives will be re-executed. If any of the
SourceFiles declares a module, FileSpec too will behave as
a module-file and export the predicates listed in the first module
declaration encountered in SourceFiles. See ref-sls.