https://www.codewars.com/kata/523f5d21c841566fde000009/train/rust
Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.
It should remove all values from list a, which are present in list b keeping their order.
array_diff(vec![1,2], vec![1]) == vec![2]If a value is present in b, all of its occurrences must be removed from the other:
array_diff(vec![1,2,2,2,3], vec![2]) == vec![1,3]