2124. Check if All A's Appears Before All B's

class Solution {
    public boolean helper(String s) {
        for(int i = 0; i < s.length() - 1; i++) {
            if(s.charAt(i) == 'b') {
                if(s.charAt(i + 1) != 'b') {
                    return false;
                }
            }
        }
        return true;
    }
    public boolean checkString(String s) {
        return helper(s);
    }
}