public void addSymbol(Symbol a) {
		Symbol res = tree.put(a.getName(),a);
		if (res != null)
			throw new SleighException("Duplicate symbol");
	}
A single scope of symbol names for sleigh
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/processors/sleigh/symbol/SymbolScope.java