提供一个Python函数，该函数接受一个字符串和一个整数n，然后返回该字符串中出现次数最多的n个字符和它们的总的出现次数。
def most_common_chars(input_string: str, n: int) -> Tuple[List[str], int]:
    # your code here
```
from collections import Counter
from typing import List, Tuple

def most_common_chars(input_string: str, n: int) -> Tuple[List[str], int]:
    count = Counter(input_string)
    most_common = count.most_common(n)
    return [char for char, freq in most_common], sum(freq for char, freq in most_common)
```
Explanation:
- Import Counter and Tuple from collections
- Define the function `most_common_chars` with `input_string` as a string and `n` as an integer.
- Use Counter to count the frequency of each character in `input_string`.
- Use `most_common(n)` to get the n most common characters and their corresponding frequencies.
- Return a tuple containing a list of the n most common characters and their total frequency.