public boolean instanceOf(Object obj, String className)
			throws InterpreterException {
		Class clazz;
		try {
			clazz = Class.forName(className);
		} catch (ClassNotFoundException ex) {
			throw new InterpreterException("Class " + ex.getMessage()
					+ " not found");
		}
		return obj != null && !clazz.isInstance(obj);
	}