def font_switch(change_type, arg)
      case change_type
      when Worksheet::NAME          then change_font_name(arg)
      when Worksheet::SIZE          then change_font_size(arg)
      when Worksheet::COLOR         then change_font_color(arg)
      when Worksheet::ITALICS       then change_font_italics(arg)
      when Worksheet::BOLD          then change_font_bold(arg)
      when Worksheet::UNDERLINE     then change_font_underline(arg)
      when Worksheet::STRIKETHROUGH then change_font_strikethrough(arg)
      else raise 'Invalid change_type'
      end
    end
def font_switch(change_type, arg)
      case change_type
      when Worksheet::NAME          then change_font_name(arg)
      when Worksheet::SIZE          then change_font_size(arg)
      when Worksheet::COLOR         then change_font_color(arg)
      when Worksheet::ITALICS       then change_font_italics(arg)
      when Worksheet::BOLD          then change_font_bold(arg)
      when Worksheet::UNDERLINE     then change_font_underline(arg)
      when Worksheet::STRIKETHROUGH then change_font_strikethrough(arg)
      else raise 'Invalid change_type'
      end
    end
Performs correct modification based on what type of change_type is specified