Added doctests

Author: sarveshsrinath

maths/is_string_palindrome.py

@@ -42,5 +42,6 @@ def is_string_palindrome(words: str) -> bool:
     return cleaned_phrase == cleaned_phrase[::-1]
 
 if __name__ == "__main__":
-    n=input("Enter a word:-")
-    print(is_string_palindrome(n))
+    import doctest
+
+    doctest.testmod()