Python PyQt - Checkbox to uncheck all other checkboxes

I'm trying to put in some validation such that:

• When either "Select A" or "Select B" is checked, "None Selected" is automatically unchecked
• When "None Selected" is checked, both "Select A" and "Select B" are automatically unchecked

But when I run this code, clicking any checkbox will uncheck all the 3 checkboxes.

i.e. The window initializes with "None Selected" checked. But when I click "Select A", it unchecks "None Selected", which is intended, but "Select A" doesn't get checked.

What am I doing wrong?

---

import sys
import PyQt5

class Test(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        checkBoxNone = QCheckBox("None Selected")
        checkBoxA    = QCheckBox("Select A")
        checkBoxB    = QCheckBox("Select B")

        checkBoxNone.setChecked(True)
        checkBoxNone.stateChanged.connect(lambda checked: (checkBoxA.setChecked(False), checkBoxB.setChecked(False)))
        checkBoxA.stateChanged.connect(lambda checked: checkBoxNone.setChecked(False))
        checkBoxB.stateChanged.connect(lambda checked: checkBoxNone.setChecked(False))

        grid = QGridLayout()

        grid.addWidget(checkBoxNone, 1, 0)
        grid.addWidget(checkBoxA, 2, 0)
        grid.addWidget(checkBoxB, 3, 0)

        self.setLayout(grid)
        self.setWindowTitle('Test')
        self.show()

if __name__ == '__main__':
    if not QApplication.instance():
        app = QApplication(sys.argv)
    else:
        app = QApplication.instance()
    ex = Test()
    sys.exit(app.exec_())