public int getStackOffset() {
		if (varnodes != null && varnodes.length != 0) {
			Address storageAddr = getLastVarnode().getAddress();
			if (storageAddr.isStackAddress()) {
				return (int) storageAddr.getOffset();
			}
		}
		throw new UnsupportedOperationException("Storage does not have a stack varnode");
	}
@return the stack offset associated with simple stack storage or compound 
storage where the last varnode is stack, see {@link #hasStackStorage()}. 
@throws UnsupportedOperationException if storage does not have a stack varnode
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/listing/VariableStorage.java