struct timeval *timeval_store(struct timeval *tv, usec_t u);
char *format_timestamp(char *buf, size_t l, usec_t t);
+char *format_timestamp_us(char *buf, size_t l, usec_t t);
char *format_timestamp_relative(char *buf, size_t l, usec_t t);
char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy);