Palindromic Substrings

class Solution:
    def countSubstrings(self, s: str) -> int:
        res = 0

        def isPalindrome(l,r):
            count = 0
            while l >= 0 and r <len(s) and s[l] == s[r]:
                count += 1
                l -= 1
                r += 1
            return count

        for i in range(len(s)):
            res += isPalindrome(i, i) + isPalindrome(i, i+1)

        return res