Create a function that returns the majority vote in an array. A majority vote is an element that occurs > N/2 times in an array (where N is the length of the array).
majorityVote(["A", "A", "B"]) ➞ "A"
majorityVote(["A", "A", "A", "B", "C", "A"]) ➞ "A"
majorityVote(["A", "B", "B", "A", "C", "C"]) ➞ null
null.null.