Given two strings `s` and `part`, perform the following operation on `s` until all occurrences of the substring `part` are removed:

- Find the leftmost occurrence of the substring `part` and remove it from `s`.

Return `s` after removing all occurrences of `part`.

A substring is a contiguous sequence of characters in a string.

Example 1:

    Input: s = "daabcbaabcbc", part = "abc"
    Output: "dab"
    Explanation: The following operations are done:
    - s = "daabcbaabcbc", remove "abc" starting at index 2, so s = "dabaabcbc".
    - s = "dabaabcbc", remove "abc" starting at index 4, so s = "dababc".
    - s = "dababc", remove "abc" starting at index 3, so s = "dab".
    Now s has no occurrences of "abc".

Example 2:

    Input: s = "axxxxyyyyb", part = "xy"
    Output: "ab"
    Explanation: The following operations are done:
    - s = "axxxxyyyyb", remove "xy" starting at index 4 so s = "axxxyyyb".
    - s = "axxxyyyb", remove "xy" starting at index 3 so s = "axxyyb".
    - s = "axxyyb", remove "xy" starting at index 2 so s = "axyb".
    - s = "axyb", remove "xy" starting at index 1 so s = "ab".
    Now s has no occurrences of "xy".

Constraints:

- `1 <= s.length <= 1000`
- `1 <= part.length <= 1000`
- `s`​​​​​​ and `part` consists of lowercase English letters.