anchor.diff:  %% @hidden
   update_session(Type, Charge, Reserve, Now, ServiceId, ChargingKey, SessionId,
   		[#bucket{start_date = Start, end_date = Expires,
  -		attributes = [], remain_amount = Remain} | T],
  +		attributes = #{bucket_type := normal}, remain_amount = Remain} | T],
   		Acc, Charged, Reserved) when Expires /= undefined,
   		Start =/= Expires, Expires =< Now, Remain >= 0 ->
   	update_session(Type, Charge, Reserve, Now,
  
positive.code: 
  %% @hidden
  charge_session1(Type, Charge, Now, ServiceId, ChargingKey, SessionId,
  		[#bucket{end_date = Expires, attributes = [],
  		remain_amount = R} | T], Acc, Charged)
  		when R >= 0, Expires /= undefined, Expires =< Now ->
  	charge_session1(Type, Charge, Now,
  
negative.code: 			Now, lists:reverse(Acc) ++ CentsBuckets, UnitsBuckets, []);
  convert(Price, Type, Size, ServiceId, ChargingKey, SessionId, Now,
  		[#bucket{remain_amount = R, end_date = Expires,
  		attributes = #{bucket_type := normal}} | T], UnitsBuckets, Acc)
  		when R >= 0, Expires /= undefined, Expires =< Now ->
  	convert(Price, Type, Size, ServiceId, ChargingKey, SessionId,
  			Now, T, UnitsBuckets, Acc);
  