# File lib/spreadsheet/excel/writer/workbook.rb, line 357
  def write_fonts workbook, writer
    fonts = @fonts[workbook] = {}
    @formats[workbook][:writers].map{|format| format.font }.compact.uniq.each do |font|
      unless fonts.include?(font.key)
        fonts.store font.key, fonts.size
        write_font workbook, writer, font
      end
    end
  end