The XOR total of an array is defined as the bitwise `XOR` of all its elements, or `0` if the array is empty.

- For example, the XOR total of the array `[2,5,6]` is `2 XOR 5 XOR 6 = 1`.

Given an array `nums`, return the sum of all XOR totals for every subset of `nums`.

Note: Subsets with the same elements should be counted multiple times.

An array `a` is a subset of an array `b` if `a` can be obtained from `b` by deleting some (possibly zero) elements of `b`.

Example 1:

    Input: nums = [1,3]
    Output: 6
    Explanation: The 4 subsets of [1,3] are:
    - The empty subset has an XOR total of 0.
    - [1] has an XOR total of 1.
    - [3] has an XOR total of 3.
    - [1,3] has an XOR total of 1 XOR 3 = 2.
    0 + 1 + 3 + 2 = 6

Example 2:

    Input: nums = [5,1,6]
    Output: 28
    Explanation: The 8 subsets of [5,1,6] are:
    - The empty subset has an XOR total of 0.
    - [5] has an XOR total of 5.
    - [1] has an XOR total of 1.
    - [6] has an XOR total of 6.
    - [5,1] has an XOR total of 5 XOR 1 = 4.
    - [5,6] has an XOR total of 5 XOR 6 = 3.
    - [1,6] has an XOR total of 1 XOR 6 = 7.
    - [5,1,6] has an XOR total of 5 XOR 1 XOR 6 = 2.
    0 + 5 + 1 + 6 + 4 + 3 + 7 + 2 = 28

Example 3:

    Input: nums = [3,4,5,6,7,8]
    Output: 480
    Explanation: The sum of all XOR totals for every subset is 480.

Constraints:

- `1 <= nums.length <= 12`
- `1 <= nums[i] <= 20`