anchor.diff:  
   -spec get_products() -> Result
   	when
  -		Result :: [#subscriber{}] | {error, Reason},
  +		Result :: [#product{}] | {error, Reason},
   		Reason :: term().
   %% @doc Get all entries in the product table.
   get_products() ->
  
positive.code: 	when
  		ProductID :: string(),
  		Result :: ok.
  %% @doc Delete an entry form the product table
  delete_product(ProductID) ->
  	F = fun() ->
  		mnesia:delete(product, ProductID, write)
  
negative.code: 		Product :: #product{},
  		Result :: ok | {error, Reason},
  		Reason :: term().
  %% @doc Add a new entry in product table.
  add_product(Product) ->
  	F = fun() ->
  		mnesia:write(product, Product, write)
  