Loads the specified Prolog source and/or object file(s) into memory, if not already loaded and up to date.
A file specification or a list of file specifications; extension optional.
The recommended style is to use this predicate for non-module-files only, but if any module-files are encountered, their public predicates are imported.
This predicate is defined as if by:
ensure_loaded(Files) :- load_files(Files, [if(changed)]).