An integer array is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same.

- For example, `[1,3,5,7,9]`, `[7,7,7,7]`, and `[3,-1,-5,-9]` are arithmetic sequences.

Given an integer array `nums`, return the number of arithmetic subarrays of `nums`.

A subarray is a contiguous subsequence of the array.

Example 1:

    Input: nums = [1,2,3,4]
    Output: 3
    Explanation: We have 3 arithmetic slices in nums: [1, 2, 3], [2, 3, 4] and [1,2,3,4] itself.

Example 2:

    Input: nums = [1]
    Output: 0

Constraints:

- `1 <= nums.length <= 5000`
- `-1000 <= nums[i] <= 1000`