Polar Signal get map function doesn't work

[Carter Francis]

When you have Power Signal you should be able to get a map of the symmetries from the Power Signal and currently it throws an error.

Make sure the three cases all work as expected:
(Make an explicit test for these three cases)

ps.get_map(k_region =[3.0,6.0]) #Sums over the k region 3.0-6.0 and for all symmetries ps.get_map(k_region =[3.0,6.0], symmetry=10) #Sums over the k region 3.0-6.0, symmetries=10 ps.get_map(k_region =[3.0,6.0], symmetry=[8,9,10]) #Sums over the k region 3.0-6.0, symmetries=8-10
It might be as simple as the symmetry needs to be written not as a list but as a set eg. [ ] vs ( )