Valid Parenthesis

valid_parenthesis_1.py

class Solution:
    def isValid(self, s: str) -> bool:
        stack = []
        for i, k in enumerate(s):
            if k == '{' or k == '(' or k == '[':
                stack.append(k)
            else:
                if not stack:
                    return False
                else:
                    top = stack.pop()
                    if (k == '}' and top != '{') or (k == ')' and top != '(') or (k == ']' and top !='['):
                        return False
        
        return len(stack) == 0