def METHOD_NAME(self, msg) -> float:
    timespec = msg.get_nla(KtestMsgAttrType.KTEST_MSG_ATTR_TS).ts
    epoch_ktime = timespec.tv_sec * 1.0 + timespec.tv_nsec * 1.0 / 1000000000
    if not hasattr(self, "_start_epoch"):
        self._start_ktime = epoch_ktime
        self._start_time = time.time()
        epoch_time = self._start_time
    else:
        epoch_time = time.time() - self._start_time + epoch_ktime
    return epoch_time