Update is_palindrome.py (TheAlgorithms#2025)

* Update is_palindrome.py

* Update is_palindrome.py

* Reuse s

Co-authored-by: Christian Clauss <cclauss@me.com>

Author: ashwindasr

strings/is_palindrome.py

@@ -1,4 +1,4 @@
-def is_palindrome(s):
+def is_palindrome(s: str) -> bool:
     """
     Determine whether the string is palindrome
     :param s:
@@ -7,7 +7,16 @@ def is_palindrome(s):
     True
     >>> is_palindrome("Hello")
     False
+    >>> is_palindrome("Able was I ere I saw Elba")
+    True
+    >>> is_palindrome("racecar")
+    True
+    >>> is_palindrome("Mr. Owl ate my metal worm?")
+    True
     """
+    # Since Punctuation, capitalization, and spaces are usually ignored while checking Palindrome,
+    # we first remove them from our string.
+    s = "".join([character for character in s.lower() if character.isalnum()])
     return s == s[::-1]