# Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
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# Note: For the purpose of this problem, we define empty string as valid palindrome.
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# Example 1:
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# Input: "A man, a plan, a canal: Panama"
# Output: true
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# Example 2:
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# Input: "race a car"
# Output: false
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# Constraints:
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# 	s consists only of printable ASCII characters.
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class Solution:
    def isPalindrome(self, s: str) -> bool:
        x=''.join(str for str in s if (str.isalpha() or str.isdigit()))
        return x.lower()==x[::-1].lower()
