Error closing Lib()

Question

I’m making an implementation of lib pjsua to work with Voip using python.

from datetime import datetime
from time import sleep
from sys import exit

from pysip.callbacks import AbstractCallCallback, AbstractAccountCallback
from pysip.states import CallState, MediaState
from pysip import Worker, GenericError

now = (lambda: datetime.now().strftime("%H:%M:%S.%f"))
class AccountCallback(AbstractAccountCallback):
    def on_incoming_call(self, call):
        callid = call.info().sip_call_id
        print(f'{now} - {callid} - Nova chamada recebida.')
        call.answer(486, "Busy")

class CallCallback(AbstractCallCallback):
    def on_state(self):
        info = self.call.info()
        callid = info.sip_call_id
        if info.state == CallState.DISCONNECTED:
            print(f'{now()} - {callid} - Chamada finalizada.')
        else:
            print(f'{now()} - {callid} - Estado alterado. Novo estado: {info.state_text}')
            print(f'{now()} - {callid} - Sinalzação: {info.last_code} {info.last_reason}')

    def on_media_state(self):
        info = self.call.info()
        callid = info.sip_call_id
        if info.media_state == MediaState.ACTIVE:
            Worker.instance().conf_connect(info.conf_slot, 0)
            Worker.instance().conf_connect(0, info.conf_slot)
            print(f'{now()} - {callid} - Mídia ativada.')
        else:
            print(f'{now()} - {callid} - Mídia desativada.')

def make_call(acc, destiny):
    worker = Worker(logfile='registros.log')
    with worker as runner:
        account_cb = CallCallback()
        account = runner.make_account(**acc)
        call = account.make_call(dst_uri=destiny, cb=account_cb)
        callid = call.info().sip_call_id
        sleep(5)
        call.hangup()

    return call.info().sip_call_id
if __name__ == '__main__':
    destiny = 'sip:[email protected]'
    acc = {'username': '1000',
            'domain': 'development',
            'password': '1000',
            'callback': AccountCallback}
    try:
        callid = make_call(acc, destiny)
        print(f'Chamada realizada: {callid}') 
    except GenericError as error:
        print(error)

In this code I was able to generate a full connection and even make the audio exchange, but after the N seconds of Sleep of the code, the call is terminated as requested, however, the script is not terminated and the python remains locked until I kill the process in another terminal tab.

All code used is in the above mentioned repository. I preferred to link the code to post here, because instead of an isolated block, there it is possible to see the script as a whole.