Fix Python – How do I get the day of week given a date?

I want to find out the following:
given a date (datetime object), what is the corresponding day of the week?
For instance, Sunday is the first day, Monday: second day.. and so on
And then if the input is something like today’s date.
Example
>>> today = datetime.datetime(2017, 10, 20)
>>> today.get_weekday() # what I look for

The output is maybe ….