In python: A palindrome is a sequence of characters which reads the same backward or forward, e.g "rotator", "madam" and "1221". Write a function isPalindrome which accepts one input string and returns the boolean value True if the string is a palindrome, and False otherwise. Your function should ignore letter case: "madam" and "Madam" are both palindromes. Note: The function should return the desired output regardless of the input string size.