Add a trigger directly to the Qmenu Object

Question

from PyQt5.QtWidgets import *
from PyQt5 import QtWidgets, QtGui


class helpwindow(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('Avirs Help')
        self.setGeometry(450, 350, 150, 600)
        self.ui()


class mainwin(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('Qmenu')
        self.setGeometry(340, 340, 360, 700)
        self.ui()

    def ui(self):
        self.mainMenu = self.menuBar()
        self.project = QLabel()
        self.fileMenu = self.mainMenu.addMenu('File')
        self.fileMenu.addAction('Add File')
        self.aboutus = self.mainMenu.addMenu('About us')
        self.aboutus.triggered.connect(self.helpwindow) # this is where the problem is, i think

        # self.fileMenu.triggered.connect(self.loadImageFromFile)

    def helpwindow(self):
        self.newwin = helpwindow()
        self.close()


def main():
    app = QApplication([])
    win = mainwin()
    win.show()
    app.exec()


if __name__ == "__main__":
    main()

I don't want to add a new tab to the menu object, I just want to trigger a new window when the "about us" menu button is clicked. i know i could add an action button to it, but I don't think it is intuitive to do that for ab "about us" button