如何在委托中检查QTreeViews项是展开还是折叠？

from PyQt5.QtWidgets import QStyledItemDelegate, QStyleOptionViewItem, QTreeView, QApplication
from PyQt5.QtCore import Qt
import sys

class CustomDelegate(QStyledItemDelegate):
    def paint(self, painter, option, index):
        # 绘制项的背景
        painter.fillRect(option.rect, option.palette.color(option.palette.Base))

        # 获取QStyleOptionViewItem对象
        item_option = QStyleOptionViewItem(option)
        self.initStyleOption(item_option, index)

        # 检查项是否展开
        if item_option.open:
            print("该项是展开的")
        else:
            print("该项是折叠的")

        # 绘制项的文本
        self.drawDisplay(painter, item_option, item_option.rect, item_option.displayAlignment)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    treeView = QTreeView()
    delegate = CustomDelegate()
    treeView.setItemDelegate(delegate)
    treeView.show()
    sys.exit(app.exec_())