void trns_chain_append (struct trns_chain *, trns_finalize_func *,
trns_proc_func *, trns_free_func *, void *);
size_t trns_chain_next (struct trns_chain *);
void trns_chain_append (struct trns_chain *, trns_finalize_func *,
trns_proc_func *, trns_free_func *, void *);
size_t trns_chain_next (struct trns_chain *);