YubiKey locking if unplugged

autolock.py

#!/usr/bin/env python3
import time
import subprocess
from datetime import datetime
from datetime import timedelta


def lock():
    subprocess.check_call("""osascript -e 'tell application "System Events" to start current screen saver'""", shell=True, stderr=subprocess.STDOUT)

def check():
    try:
        subprocess.check_call('ioreg -p IOUSB | grep Yubikey > /dev/null', shell=True)
        return True
    except:
        return False

def main():
    locked_before = None
    plugged_in_before = None
    threshold = timedelta(seconds=60)

    while True:
        now = datetime.now()
        plugged_in_now = check()
        if plugged_in_before is None:
            plugged_in_before = plugged_in_now
        if plugged_in_before and not plugged_in_now:
            if locked_before is None or now - locked_before > threshold:
                lock()
                locked_before = now
            if now - locked_before >= threshold:
                plugged_in_before = plugged_in_now
        time.sleep(2)

if __name__ == '__main__':
    main()

com.zerokspot.yubikey-autolock.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC -//Apple Computer//DTD PLIST 1.0//EN http://www.apple.com/DTDs/PropertyList-1.0.dtd >
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.zerokspot.yubikey-autolock</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/local/bin/python3</string>
        <string>/Users/zerok/.local/bin/autolock.py</string>
    </array>
    <key>KeepAlive</key>
    <true />
  </dict>
</plist>