IsPal funciton Implement the recursive function isPal(), which determines whether a string str is a simple palindrome.

A simple palindrome is a string consisting entirely of the characters a-z that reads the same forward and backward. For instance, the upcoming are palindromes: dad, level, mom, madamimadam, . Use the following declaration of isPal(): bool isPal (const string& str, int startIndex, int endIndex);

It returns true when the substring in the index range [startIndex, endIndex) is a palindrome. The conditions are Stopping Condition: Result is true when startIndex >= endIndex -1 Result is false when str[startIndex] != str[endIndex-1]

Recursive Step: Determine whether the substring of the str in the index range [startIndex+1, endIndex-1] is a palindrome