anchor.diff:  			ProdValidity =/= {error, format_error} ->
   				{ProdUnits, ProdSize} = product_unit_of_measure(ProdUOMesasure),
   				Size = product_size(ProdUnits, octets, ProdSize),
  -				RCPeriod = recurring_charge_period(RCPeriodS),
   				Price1 = #price{name = ProdName, description = ProdDescirption,
   				type = ProdPriceType, units = ProdUnits, size = Size,
   					currency = CurrencyCode, period = RCPeriod, validity = ProdValidity,
  
positive.code: 		undefined ->
  			"";
  		RCPeriod ->
  			{"recurringChargePeriod", RCPeriod}
  	end.
  
  -spec prod_price_description(Prefix, Price) -> Result
  
negative.code: product_size(mb, octets, Size) -> Size * 1000000;
  product_size(_, _, Size) -> Size.
  
  -spec rc_period(RCPeriod) -> Result
  	when
  		RCPeriod	:: string(),
  		Result	:: valid_period().
  %% @doc return valid period
  %% @private
  rc_period("") -> undefined;
  rc_period("yearly") -> yearly;
  rc_period("monthly") -> monthly;
  rc_period("weekly") -> weekly;
  rc_period("daily") -> daily;
  rc_period(undefined) -> "";
  rc_period(yearly) -> "yearly";
  rc_period(monthly) -> "monthly";
  rc_period(weekly) -> "weekly";
  rc_period(daily) -> "daily".
  
  -spec find_status(StringStatus) -> Status when
  	StringStatus	:: string(),
  