__isl_give isl_set *isl_set_substitute(__isl_take isl_set *set,
enum isl_dim_type type, unsigned pos, __isl_keep isl_aff *subs);
__isl_give isl_set *isl_set_substitute(__isl_take isl_set *set,
enum isl_dim_type type, unsigned pos, __isl_keep isl_aff *subs);