# File lib/gettext/tools/msgmerge.rb, line 322
        def parse(command_line)
          parser = create_option_parser
          rest = parser.parse(command_line)

          if rest.size != 2
            puts(parser.help)
            exit(false)
          end

          @definition_po, @reference_pot = rest
          @output = @definition_po if @update
        end