Function spin

19-concurrency/spinner_async.py:11–20

(msg: str)

import itertools

async def spin(msg: str) -> None:  # <1>
    for char in itertools.cycle(r'\|/-'):
        status = f'\r{char} {msg}'
        print(status, flush=True, end='')
        try:
            await asyncio.sleep(.1)  # <2>
        except asyncio.CancelledError:  # <3>
            break
    blanks = ' ' * len(status)
    print(f'\r{blanks}\r', end='')

async def slow() -> int:
    await asyncio.sleep(3)  # <4>