Recursive palindrome check - having issues when recalling the function - python-3.x

Question

The problem is simple, check if palindrome or not using recursion. They also provided a template so I can't change that.
The template:
def isPalindrome(s): # Wrapper function
def isPalindromeRec(s,low,high):
""" Recursive function which checks if substring s[low ... high] is palindrome
returns a True/False value"""
n = len(s)
return isPalindromeRec(s,0,n-1)
I am nearly there but I think I am having trouble understanding how recursion exactly works. (especially how the values changes in the recursion)
My code:
def isPalindrome(s): # Wrapper function
def isPalindromeRec(s,low,high):
if len(s)<=1:
return True
else:
if s[0]==s[len(s)-1]:
return isPalindromeRec(s[low+1:high],low+1,high-1)
else:
return False
n = len(s)
return isPalindromeRec(s,0,n-1)
print(isPalindrome("anna"))
print(isPalindrome("civic"))
print(isPalindrome("a"))
print(isPalindrome("tx1aa1xt"))
print(isPalindrome(""))
print(isPalindrome("Civic"))
print(isPalindrome("ab"))
this is the output:
runfile('/Users/Rayan/Desktop/AUB Spring 2019/EECE 230 /HW/Homework 7/Problem2.py', wdir='/Users/Rayan/Desktop/AUB Spring 2019/EECE 230 /HW/Homework 7')
True
True
True
False
True
False
False
the first false should be True.
Thank you for your help!

Answer 1

Rewrote it:
def isPalindrome(s):
def isPalindromeRec(s,low,high):
if (low == high):
return True
if (s[low] != s[high]) :
return False
if (low < high + 1) :
return isPalindromeRec(s, low + 1, high - 1);
return True
n = len(s)
if (n == 0) :
return True
return isPalindromeRec(s, 0, n - 1);
print(isPalindrome("anna"))
print(isPalindrome("civic"))
print(isPalindrome("a"))
print(isPalindrome("tx1aa1xt"))
print(isPalindrome(""))
print(isPalindrome("Civic"))
print(isPalindrome("ab"))
output:
True
True
True
True
True
False
False