You are given an array `nums` that consists of non-negative integers. Let us define `rev(x)` as the reverse of the non-negative integer `x`. For example, `rev(123) = 321`, and `rev(120) = 21`. A pair of indices `(i, j)` is nice if it satisfies all of the following conditions:

- `0 <= i < j < nums.length`
- `nums[i] + rev(nums[j]) == nums[j] + rev(nums[i])`

Return the number of nice pairs of indices. Since that number can be too large, return it modulo `109 + 7`.

Example 1:

    Input: nums = [42,11,1,97]
    Output: 2
    Explanation: The two pairs are:
     - (0,3) : 42 + rev(97) = 42 + 79 = 121, 97 + rev(42) = 97 + 24 = 121.
     - (1,2) : 11 + rev(1) = 11 + 1 = 12, 1 + rev(11) = 1 + 11 = 12.

Example 2:

    Input: nums = [13,10,35,24,76]
    Output: 4

Constraints:

- `1 <= nums.length <= 105`
- `0 <= nums[i] <= 109`