Introduce several ways to judge whether an word is a parlindrome.

is_palindrome.py

# 1. basic: using for loop
def is_palindrome_basic(word):
    SIZE = len(word)
    for i in range(SIZE // 2):
        if word[i] != word[SIZE-1-i]:
            return False
    return True
    
    
# 2. Pythonic way: reversing word easily
def is_palindrome_reverse(word):
    return word == word[::-1]
    
    
# 3. recursion: function call
def is_palindrome_recursive(word):
    def compare(lo, hi):
        if lo >= hi:
            return True
        
        if word[lo] == word[hi]:
            return compare(lo+1, hi-1)
        else:
            return False
    
    return compare(0, len(word)-1)