extern uint16_t rrand(char, uint32_t);
extern void update_log (struct World *, char *);
extern uint16_t center_offset (uint16_t, uint16_t, uint16_t);
extern uint16_t rrand(char, uint32_t);
extern void update_log (struct World *, char *);
extern uint16_t center_offset (uint16_t, uint16_t, uint16_t);