int uc_get_history(const data_set_t *ds, const value_list_t *vl,
gauge_t *ret_history, size_t num_steps, size_t num_ds);
int uc_get_history_by_name(const char *name, gauge_t *ret_history,
int uc_get_history(const data_set_t *ds, const value_list_t *vl,
gauge_t *ret_history, size_t num_steps, size_t num_ds);
int uc_get_history_by_name(const char *name, gauge_t *ret_history,