def load_products
    File.open(@input_database, "r") do |file|
     product_list = REXML::Document.new(file)
     product_list.root.elements.each do |product_elements|
       code = student_element.elements["product code"].text
       name = student_element.elements["name"].text
       price = student_element.elements["price"].text
       product = Produkt.new(code, name, price)
     end
    end