TransUnion's TruVision products process short labels that may need palindrome validation before display. Write a reusable function that determines whether a given word is a palindrome.
A palindrome reads identically from left to right and right to left. The comparison must be case-insensitive, so Radar is a palindrome. The input contains only alphabetic characters, so no punctuation or whitespace needs to be removed.
Use a string as the input data structure and implement the comparison with two pointers, one starting at each end. Return True when the word is a palindrome and False otherwise.
Implement is_palindrome(word), where word is a non-empty string. The function must return a Boolean value. It must not modify the input string.
def is_palindrome(word):