int uc_meta_data_add_double(const value_list_t *vl, const char *key,
double value);
int uc_meta_data_add_boolean(const value_list_t *vl, const char *key,
int uc_meta_data_add_double(const value_list_t *vl, const char *key,
double value);
int uc_meta_data_add_boolean(const value_list_t *vl, const char *key,