def index_of_match_after_additions
      return unless expected_additions > 0

      (1..expected_additions).each do |i|
        next_difference = item_difference(
          old_array[old_index],
          new_array[new_index + i],
          old_index
        )

        return new_index + i if next_difference.empty?
      end

      nil
    end
def index_of_match_after_additions
      return unless expected_additions > 0

      (1..expected_additions).each do |i|
        next_difference = item_difference(
          old_array[old_index],
          new_array[new_index + i],
          old_index
        )

        return new_index + i if next_difference.empty?
      end

      nil
    end
look ahead in the new array to see if the current item appears later
 thereby having new items added