Write a recursive function named checkPalindrome that takes a string as input, and returns true if the string is a palindrome and false if it is not a palindrome. A string is a palindrome if it reads the same forwards or backwards. Recall that str. charAt(a) will return the character at position a in str. str. substring(a) will return the substring of str from position a to the end of str, while str. substring(a, b) will return the substring of str starting at position a and continuing to (but not including) the character at position b