Find the majority element in an array

majority.py

def get_majority(A, k):
    """
    Return the majority element in an array. O(n) time.
    This is an implementation of Moore's voting algorithm.
    """
    maj_index = 0
    count = 1

    for i in range (1, len(A-1)):
        # If the current element is equal to the index of the majority element, increment count
        if A[maj_index] == A[i]:
            count += 1
        # Otherwise decrement count
        else:
            count -= 1
        
        # If the count is zero, it's not the max element, so set the majority index to the
        # current index and increment the count
        if count == 0:
            maj_index = i
            count = 1
            
    # Check that the number of times the elemnt occurs is actually a majority 
    if count > n/2:
        return A[maj_index]
    else:
        return None
    

This algorithm only works when the amount of majority more than half length of array.