def flattened
      ff=Workbook::Format.new()
      formats.each{|a| ff.merge!(a) }
      return ff
    end
def flattened
      ff=Workbook::Format.new()
      formats.each{|a| ff.merge!(a) }
      return ff
    end
Applies the formatting options of self with its parents until no parent can be found
 @return [Workbook::Format] new Workbook::Format that is the result of merging current style with all its parent's styles.