anchor.diff:  		MultiSessions :: boolean() | undefined,
   		Result :: {ok, #service{}} | {error, Reason},
   		Reason :: term().
  -%% @doc Create an entry in the subscriber table.
  +%% @doc Create an entry in the service table.
   %%
   %% 	Authentication will be done using `Password'. An optional list of
   %% 	RADIUS `Attributes', to be returned in an `AccessRequest' response,
  
positive.code: 		update_client/2, update_client/3, get_clients/0, delete_client/1,
  		query_clients/6]).
  -export([add_service/3, add_service/4, add_service/5,
  		add_service/6, add_service/8,
  		find_service/1, delete_service/1, update_password/2,
  		get_services/0, query_service/1]).
  -export([add_user/3, list_users/0, get_user/1, delete_user/1,
  		query_users/3, update_user/3]).
  -export([add_product/1, find_product/1, get_products/0, delete_product/1,
  
negative.code: 	NewBuckets = charge(SubscriptionAmount + AllowanceAmount,
  			[#bucket{units = Units, remain_amount = Size, name = Name,
  			termination_date = end_period(Now, Period)} | Buckets]),
  	subscription(Service#service{buckets = NewBuckets},
  			Characteristics, Now, InitialFlag, T);
  subscription(#service{buckets = Buckets} = Service,
  		Characteristics, Now, InitialFlag, [#price{type = usage,
  		name = Name, alteration = #alteration{type = recurring,
  		period = Period, units = Units, size = Size,
  