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package horstmann.ch05_invoice;
/**
   This interface describes the tasks that an invoice
   formatter needs to carry out.
 */
public interface InvoiceFormatter
{
  /**
      Formats the header of the invoice.
      @return the invoice header
   */
  String formatHeader();

  /**
      Formats a line item of the invoice.
      @return the formatted line item
   */
  String formatLineItem(LineItem item);

  /**
      Formats the footer of the invoice.
      @return the invoice footer
   */
  String formatFooter();
}