In Python, we could take advantage of the Counter() class from the 'collections' library to get the frequency of each character instead of doing it manually. Any tips for improving the following candidate solution would be great:

from collections import Counter

class Solution:
    def firstUniqChar(self, s: str) -> int:
        characters_count = Counter(s)

        for index, character in enumerate(s):
            if characters_count[character] == 1:
                return index
        
        return -1