Exses and Ohs

Question

Check to see if a string has the same amount of 'x's and 'o's. The method must return a boolean and be case insensitive. The string can contain any char.

Examples input/output:

XO("ooxx") => true
XO("xooxx") => false
XO("ooxXm") => true
XO("zpzpzpp") => true // when no 'x' and 'o' is present should return true
XO("zzoo") => false

Here is my code please explain why 26 test cases are right and 2 are wrong.
Check your and my code here: https://www.codewars.com/kata/55908aad6620c066bc00002a/train/JUMP_LINK__&&__python__&&__JUMP_LINK

My code:

def xo(s):
a = s.count('x')
b = s.count('o')
if a == b:
return True
elif 'x' and 'o' not in s:
return True
else:
return False

Answer 1

1. Your solution isn't case insensitive (unless you're altering the string prior to calling the function)
s = s.lower()

2. You don't need the if-elif-else block and can just;
return s.count('x') == s.count('o')

def xo(s):
s = s.lower()
return s.count('x') == s.count('o')