k5_once_t
typedef struct { k5_once_t once; int error, did_run; void (*fn)(void); } k5_init_t;
int k5_once(k5_once_t *once, void (*fn)(void));
k5_once(k5_once_t *once, void (*fn)(void))
int k5_once(k5_once_t *once, void (*fn)(void));
k5_once(k5_once_t *once, void (*fn)(void))