Given an array of integers `arr`, return `true` if the number of occurrences of each value in the array is unique, or `false` otherwise.

Example 1:

    Input: arr = [1,2,2,1,1,3]
    Output: true
    Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.

Example 2:

    Input: arr = [1,2]
    Output: false

Example 3:

    Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
    Output: true

Constraints:

- `1 <= arr.length <= 1000`
- `-1000 <= arr[i] <= 1000`