Register function to show one alert at a time

serial_alert.py

import asyncio
import iterm2

pending = False
last_coro = None

async def main(connection):
    loop = asyncio.get_event_loop()

    async def really_notify(message, window_id):
        global pending
        alert = iterm2.Alert("Hey", message, window_id)
        pending = True
        await alert.async_run(connection)
        # Sleep for a sec so you can hit control-c for a runaway job
        await asyncio.sleep(1)
        pending = False

    @iterm2.RPC
    async def notify(message, window_id=iterm2.Reference("tab.window.id")):
        if pending:
            return
        global last_coro
        if last_coro:
            await last_coro
        last_coro = loop.create_task(really_notify(message, window_id))
    await notify.async_register(connection)

iterm2.run_forever(main)