Please solve the programming task below using a self-contained code snippet in a markdown code block.

Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.
You may assume the given input string is always valid. For example, "01:34", "12:09" are all valid. "1:34", "12:9" are all invalid.
 
Please complete the following python code precisely:
```python
class Solution:
    def nextClosestTime(self, time: str) -> str:
```