Given a nested list of integers, return the sum of all integers in the list weighted by their depth.
Each element is either an integer, or a list -- whose elements may also be integers or other lists.
Example 1:
Input: [[1,1],2,[1,1]] Output: 10 Explanation: Four 1's at depth 2, one 2 at depth 1.
Example 2:
Input: [1,[4,[6]]] Output: 27 Explanation: One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4*2 + 6*3 = 27.