static Lifespan before(long snap) {
		if (snap == DOMAIN.lmin()) {
			return EMPTY;
		}
		return DOMAIN.atMost(DOMAIN.dec(snap));
	}
Get the lifespan that excludes the given and all future snaps

@param snap the snap
@return the lifespan
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/Lifespan.java