code: def media_file_set(type, link_type, value)
        media = media_file(type)
  
        # create a new isbn record if we need to
        if media.nil?
          media = ONIX::MediaFile.new
          media.media_file_type_code = type
          media.media_file_link_type_code = link_type
          product.media_files << media
        end
  
        # store the new value
        media.media_file_link = value.to_s
      end
docs: set the value of a particular ID