def get_unique_values(known_values, new_values):
    """ Compare two lists, counts and returns unique elements not found in known values """
    unique_values = []
    # Note: new_list = list[:] signals that we want a copy of the original list,
    #       otherwise using new_list.remove() lower down would alter both lists
    unique_values = new_values[:]
    unique_count = 0

    for k_value in known_values:
        for current_item in unique_values:

            if current_item == k_value:
                unique_values.remove(current_item)
                unique_count += 1

    return unique_values