Changing colour of Tkintermapview Polygon during run

I am creating a program that requires changing the colour of a polygon using tkintermapview during the program. I have tried the following:

polygon1 = map_widget.set_polygon([(52, -1),
                                   (52.5, -1.1),
                                   (52.2, -1.5)],
                                  fill_color = 'red',
                                  name='Test location')

polygon1.fill_color = 'black'



However, the colour on the map does not change from red to black. How would I achieve the desired outcome?