Python - PyQt - MyCheckBox

#!/usr/bin/env python

#
# https://www.reddit.com/r/learnpython/comments/4wkzva/pyqt_child_of_qcheckbox_with_additional_argument/
#

from __future__ import print_function
import sys
from PyQt4 import QtGui, QtCore


class Window(QtGui.QDialog):

    def __init__(self, window):
        super(Window, self).__init__() # space after `,`
        self.mw = window
        self.setGeometry(50, 50, 500, 300) # space after `,`
        self.setWindowTitle("PQ status!")

        self.letters_checked = [] # lower_case name
        self.all_letters = ['a','b','c','d','e'] # space after `,`  # lower_case name

        self.home()
        self.show()

    def home(self):
        # pythonic method to work with list
        for index, letter in enumerate(self.all_letters):
            self.checkBox = MyCheckBox(letter, self)
            self.checkBox.stateChanged.connect(self.checkBox.add_or_remove_letter)
            self.checkBox.move(20, 20*index)


class MyCheckBox(QtGui.QCheckBox):

    def __init__(self, text, window):
        self.text = text
        self.window = window # add to class to use `self.window` instead of global `window`
        super(MyCheckBox, self).__init__(text, window) # need parent `window/widget`

    def add_or_remove_letter(self, state):
        if state == QtCore.Qt.Checked:
            self.window.letters_checked.append(self.text) # with `self.`
        elif self.text in self.window.letters_checked: # `test` without () # there is no `deck`
            self.window.letters_checked.remove(self.text) # with `self.`

        print('[DEBUG] letters_checked:', ', '.join(self.window.letters_checked))


if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    GUI = Window(QtGui.QMainWindow)
    app.exec_()