How do I pass a variable to a QThread object when creating an instance? I'm getting a type error in Qthread.__init__ - qthread

Question

I found this sample code using QThread at https://doc.qt.io/qtforpython/examples/example_widgets__thread_signals.html
I modified the code in an attempt to pass a variable to the thread when instantiated based on info I found here: https://nikolak.com/pyqt-threading-tutorial/
Unfortunately I am getting the following error:
Traceback (most recent call last):
File "C:\Users\joe\python\ThreadTest.py", line 22, in start_thread
instanced_thread = WorkerThread(self, 'c:\testfile.xml')
File "C:\Users\joe\python\ThreadTest.py", line 44, in __init__
QThread.__init__(self, parent)
TypeError: 'PySide6.QtCore.QThread.__init__' called with wrong argument types:
PySide6.QtCore.QThread.__init__(str)
Supported signatures:
PySide6.QtCore.QThread.__init__(Optional[PySide6.QtCore.QObject] = None)
Can someone tell me the proper syntax for passing a variable to a QThread?
I'm using PySide6 and Python 3.9.10.
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
import sys
from PySide6.QtCore import QObject, QThread, Signal, Slot
from PySide6.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget
# Create a basic window with a layout and a button
class MainForm(QWidget):
def __init__(self):
super().__init__()
self.setWindowTitle("My Form")
self.layout = QVBoxLayout()
self.button = QPushButton("Click me!")
self.button.clicked.connect(self.start_thread)
self.layout.addWidget(self.button)
self.setLayout(self.layout)
# Instantiate and start a new thread
def start_thread(self):
instanced_thread = WorkerThread(self, 'c:\testfile.xml')
instanced_thread.start()
# Create the Slots that will receive signals
#Slot(str)
def update_str_field(self, message):
print(message)
#Slot(int)
def update_int_field(self, value):
print(value)
# Signals must inherit QObject
class MySignals(QObject):
signal_str = Signal(str)
signal_int = Signal(int)
# Create the Worker Thread
class WorkerThread(QThread):
def __init__(self, filename, parent=None):
QThread.__init__(self, parent)
# Instantiate signals and connect signals to the slots
self.signals = MySignals()
self.signals.signal_str.connect(parent.update_str_field)
self.signals.signal_int.connect(parent.update_int_field)
self.filename = filename
def run(self):
# Do something on the worker thread
a = 1 + 1
# Emit signals whenever you want
self.signals.signal_int.emit(a)
self.signals.signal_str.emit("This text comes to Main thread from our Worker thread.")
print(self.filename)
if __name__ == "__main__":
app = QApplication(sys.argv)
window = MainForm()
window.show()
sys.exit(app.exec())