private long getNextId() {
		long key = HighSymbol.ID_BASE + uniqueSymbolId;
		uniqueSymbolId += 1;
		return key;
	}
Assign a unique id to a new symbol being put in this container.
@return the unique id
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/LocalSymbolMap.java