Create a function that takes a string, checks if it has the same number of x's and o's and returns either true or false.
true or false).true if the amount of x's and o's are the same.false if they aren't the same amount.true.XO("ooxx") ➞ true
XO("xooxx") ➞ false
XO("ooxXm") ➞ true
// Case insensitive.
XO("zpzpzpp") ➞ true
// Returns true if no x and o.
XO("zzoo") ➞ false