EcoStruxure monitoring interfaces may display short labels that need consistent validation. Write a function that determines whether a given word is a palindrome, meaning it reads the same forward and backward when letter case is ignored.
Implement is_palindrome(word), where word is a non-empty string containing only English alphabetic characters. Return True if the word is a palindrome, and False otherwise. Do not create a reversed copy of the string unless you use it in an alternative solution.
def is_palindrome(word):