anchor.diff:  
   -spec add(Vendor, Attribute, Value, Attributes) -> Attributes
   	when
  -		Vendor :: byte(),
  +		Vendor :: 1..16#ffffff,
   		Attribute :: byte(),
   		Value :: term(),
   		Attributes :: attributes().
  
positive.code: 
  -spec store(Vendor, Attribute, Value, Attributes) -> Attributes
  	when
  		Vendor :: byte(),
  		Attribute :: byte(),
  		Value :: term(),
  		Attributes :: attributes().
  
negative.code: 
  -spec fetch(Vendor, Attribute, Attributes) -> Value
  	when
  		Vendor :: 1..16#ffffff,
  		Attribute :: byte(),
  		Attributes :: attributes(),
  		Value :: term().
  