main()

键入：python print_main_function.py

# import os
# import time
import datetime
print('Hello World!')
print('Time is ', datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S %A'))
print('__name__ value: ', __name__)
def main():
    print('this message is from main function')
if __name__ == '__main__':
    main()
    # print(__name__)

键入： python print_main_module.py

import print_main_function
print("Done!")