code: protected Set access(PathAccessor pa, Set<BioPAXElement> seed, Set<BioPAXElement> all)
  	{
  		Set set = pa.getValueFromBeans(seed);
  		set.removeAll(all);
  
  		// remove blacklisted
  		if (blacklist == null) return set;
  		else return blacklist.getNonUbiqueObjects(set);
  	}
docs: Uses the given PathAccessor to access fields of the seed and return only new elements that is
  not in the given element set (all).
  @param pa accessor to the filed
  @param seed entities to get their fields
  @param all already found values
  @return new values