int uc_get_rate_by_name (const char *name, gauge_t **ret_values, size_t *ret_values_num);
gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl);
int uc_get_rate_by_name (const char *name, gauge_t **ret_values, size_t *ret_values_num);
gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl);