def national(formatted = true)
      return @national_number unless valid?
      format_match, format_string = formatting_data

      if format_match
        out = format_string.gsub(/\$\d/) { |el| format_match[el[1].to_i] }
        formatted ? out : out.gsub(/[^0-9]/, '')
      else
        @national_number
      end
    end
def national(formatted = true)
      return @national_number unless valid?
      format_match, format_string = formatting_data

      if format_match
        out = format_string.gsub(/\$\d/) { |el| format_match[el[1].to_i] }
        formatted ? out : out.gsub(/[^0-9]/, '')
      else
        @national_number
      end
    end
Returns formatted national number
 @param formatted [Boolean] whether to return numbers only or formatted
 @return [String] formatted national number