public Object get(String atrName) {
        Object ret = null;
        if (atrName.equals(LABEL)) {
            ret = e.getLabel();
        } else if (atrName.equals(STROKE)) {
            ret = e.getStroke();
        } else if (atrName.equals(COLOR)) {
            ret = e.getColor();
        } else if (atrName.equals(MARK)) {
            ret = e.getMark();
        } else if (atrName.equals(WEIGHT)) {
            ret = e.getWeight();
        } else if (atrName.equals(SHOW_WEIGHT)) {
            ret = e.isShowWeight();
        } else if (atrName.equals(LABEL_LOCATION)) {
            ret = e.getLabelLocation();
        } else if (atrName.equals(ARROW)) {
            ret = e.getArrow();
//        } else if (atrName.equals(HEAD)) {
//            ret = e.source;
//        } else if (atrName.equals(TAIL)) {
//            ret = e.target;
        } else if (atrName.equals(CURVE_CONTROL_POINT)) {
            ret = e.getCurveControlPoint();
        } else {
            ret = e.getUserDefinedAttribute(atrName);
        }
        return ret;
    }