Basic PyQt GUI impementing asyncio behavior

basic_async_qt.py

from PyQt5.QtWidgets import QProgressBar
from qasync import QApplication
import functools
import asyncio
import qasync
import sys

async def main():
    def close_future(future, loop):
        loop.call_later(10, future.cancel)
        future.cancel("Close Application")
    future = asyncio.Future()

    app = QApplication.instance()

    if hasattr(app, 'aboutToQuit'):
        getattr(app, 'aboutToQuit').connect(functools.partial(close_future, future, asyncio.get_event_loop()))

    progress = QProgressBar()
    progress.setRange(0, 99)
    progress.show()

    for i in range(100):
        progress.setValue(i)
        await asyncio.sleep(0.1)

    await future

    return True

if __name__ == "__main__":
    try:
        qasync.run(main())
    except asyncio.exceptions.CancelledError:
        sys.exit(0)