public static boolean isScratch(long snap) {
		return snap < 0;
	}
Check if a given snapshot key is designated as scratch space

<p>
Conventionally, negative snaps are scratch space.

@param snap the snap
@return true if scratch space
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/Lifespan.java