How to add numbers in side a complex array using a recurring method in Python : x = [[1,2],[3,56],[0,1],[[1, 0, 3]]]

How do I add the numbers in x using a recurring method. 
It should be able to be adopt to other complex arrays e.g if I change x to 
x = [[1,2, 56],[3,56],[0,1],[[1, 0, 3]]]

