Thanks for your solution.

I used yours because I couldn't import my numpy solution :P

arrNP = np.array(arr)

arrNPDia1 = arrNP.diagonal()
print(arrNPDia1)
sum1 = sum(arrNPDia1)

arrNPDia2 = np.diag(np.fliplr(arrNP))
print(arrNPDia2)
sum2 = sum(arrNPDia2)

# Calculate and Print Diff
result = abs(sum1 - sum2)
return result