string compression

class Solution:
    def compress(self, chars: List[str]) -> int:

        read = 0
        write = 0

        while read < len(chars):

            char = chars[read]
            count = 0
            while read < len(chars) and char == chars[read]:
                read += 1
                count += 1

            chars[write] = char
            write += 1

            if count > 1:
                for c in str(count):
                    chars[write] = c
                    write += 1

        return write