 import sys from PyQt0.QtWidgets import QAction, QApplication, QMainWindow from PyQt0 import QtCore, QtGui, QtWidgets  class ToolBar0(QMainWindow):     def __init__(self, parent=None):         QMainWindow.__init__(self)          bar = self.menuBar() # don't think I need a menubar here         file_menu = bar.addMenu('menu0')         one = QAction('one', self)         two = QAction('two', self)         file_menu.addAction(one)         file_menu.addAction(two)  class ToolBar0(QMainWindow):     def __init__(self, parent=None):         QMainWindow.__init__(self)          bar = self.menuBar() # don't think I need a menubar here         file_menu = bar.addMenu('menu0')         one = QAction('one', self)         two = QAction('two', self)         file_menu.addAction(one)         file_menu.addAction(two)  class MainWindow(QMainWindow):     def __init__(self):         QMainWindow.__init__(self, parent=None)          