anchor.diff:  		when is_list(Password) ->
   	add_subscriber(Identity, list_to_binary(Password), Attributes, Balance,
   			EnabledStatus, MSessions);
  -add_subscriber(undefined, Password, Attributes, Balance, EnabledStatus, MSessions) ->
  +add_subscriber(undefined, Password, Attributes, Balance, EnabledStatus, MSessions)
  +		when is_binary(Password), is_list(Attributes), is_integer(Balance),
  +		Balance >= 0, is_boolean(EnabledStatus), is_boolean(MSessions) ->
   	F2 = fun() ->
   				F1 = fun(_, _, 0) ->
   							mnesia:abort(retries);
  
positive.code: 	end;
  add_subscriber(Identity, Password, Attributes, Balance, EnabledStatus, MSessions)
  		when is_binary(Identity), is_binary(Password), is_list(Attributes),
  		is_integer(Balance), Balance >= 0, is_boolean(EnabledStatus) ->
  	F1 = fun() ->
  				S = #subscriber{name = Identity, password = Password,
  						attributes = Attributes, balance = Balance,
  
negative.code: 			{ok, Subscriber};
  		{aborted, Reason} ->
  			{error, Reason}
  	end.
  
  -spec find_subscriber(Identity) -> Result  
  	when
  