https://www.guru99.com/date-time-and-datetime-classes-in-python.html
https://www.saltycrane.com/blog/2008/06/how-to-get-current-date-and-time-in/
https://stackabuse.com/how-to-format-dates-in-python/
http://www.pressthered.com/adding_dates_and_times_in_python/