I need to get a list of Mondays within a date range. 

For example:

```
# selected date range
date_range = ['2019-02-25', '2019-03-25']
# desired output:
mondays = ['2019-02-25', '2019-03-04', '2019-03-11', '2019-03-18', '2019-03-25']

# selected date range
date_range = ['2019-02-25', '2019-03-20']
# desired output
mondays = ['2019-02-25', '2019-03-04', '2019-03-11', '2019-03-18']

```

The starting date is always a Monday. 

Does anyone know how I can generate the list of Mondays using python datetime?