#!/usr/bin/env python# -*- coding: utf-8 -*-import asyncioimport datetimeimport timedef function_1(end_time, loop):    print("function_1 called")    if (loop.time() + 1.0) < end_time:        loop.call_later(1, function_2, end_time, loop)    else:        loop.stop()        def function_2(end_time, loop):    print("function_2 called")    if (loop.time() + 1.0) < end_time:        loop.call_later(1, function_3, end_time, loop)    else:        loop.stop()def function_3(end_time, loop):    print("function_3 called")    if (loop.time() + 1.0) < end_time:        loop.call_later(1, function_1, end_time, loop)    else:        loop.stop()def function_4(end_time, loop):    print("function_4 called")    if (loop.time() + 1.0) < end_time:        loop.call_later(1, function_4, end_time, loop)    else:        loop.stop()loop = asyncio.get_event_loop()end_loop = loop.time() + 9.0loop.call_soon(function_1, end_loop, loop)# loop.call_soon(function_4, end_loop, loop)loop.run_forever()loop.close()