extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
gl_setelement_compar_fn compar_fn,
gl_setelement_dispose_fn dispose_fn);
extern bool gl_oset_add (gl_oset_t set, const void *elt);
extern gl_oset_t gl_oset_create_empty (gl_oset_implementation_t implementation,
gl_setelement_compar_fn compar_fn,
gl_setelement_dispose_fn dispose_fn);
extern bool gl_oset_add (gl_oset_t set, const void *elt);