_STACK *sk_new_null(void);
void sk_free(_STACK *);
void sk_pop_free(_STACK *st, void (*func)(void *));
+_STACK *sk_deep_copy(_STACK *, void *(*)(void *), void (*)(void *));
int sk_insert(_STACK *sk, void *data, int where);
void *sk_delete(_STACK *st, int loc);
void *sk_delete_ptr(_STACK *st, void *p);