Fix: add doctests and descriptive parameter for is_palindrome

strings/is_palindrome.py

@@ -0,0 +1,24 @@
+def is_palindrome(input_string: str) -> bool:
+    """
+    Check if a given string is a palindrome.
+
+    A palindrome is a string that reads the same forward and backward.
+
+    Args:
+        input_string (str): The string to check.
+
+    Returns:
+        bool: True if the string is a palindrome, False otherwise.
+
+    Examples:
+        >>> is_palindrome("madam")
+        True
+        >>> is_palindrome("hello")
+        False
+        >>> is_palindrome("racecar")
+        True
+        >>> is_palindrome("12321")
+        True
+    """
+    normalized = input_string.lower().replace(" ", "")
+    return normalized == normalized[::-1]