How to add window to mdiArea d PyQt5?

Question

Python

Hello.
Knowing please tell me how to add windows to mdiArea.
Here I sketched a very simple example, but it does not work for me. I roughly understand why it doesn't work but I don't know how to fix it.
QtDesiner

Code

import sys
from PyQt5.QtWidgets import *
from PyQt5 import QtGui, QtCore
from PyQt5.uic import loadUiType

app = QApplication(sys.argv)
main_class, base_class = loadUiType('main.ui')
dialog_1_class, dialog_1_base_class = loadUiType("dialog.ui")


class MainWindow(QMainWindow, main_class):
    def __init__(self, *args):
        super(MainWindow, self).__init__(*args)
        self.setupUi(self)
        dialog1 = Dialog
        self.mdiArea.addSubWindow(dialog1)


class Dialog(QWidget, dialog_1_class):
    def __init__(self, *args):
        super(Dialog, self).__init__(*args)
        self.setupUi(self)

main = MainWindow()
main.show()
sys.exit(app.exec_())

Code screenshot + error Error

text - TypeError: QMdiArea.addSubWindow(QWidget, Qt.WindowFlags flags=0): argument 1 has unexpected type 'PyQt5.QtCore.pyqtWrapperType'

Answer 1

I found how to fix everything.
It is necessary to put brackets
How did I get so fucked up!