public List<Guitar> searchGuitar(GuitarSpec searchGuitarSpec ) {
	List<Guitar> matchingGuitars = new ArrayList<Guitar>();
	for (Iterator<Guitar> i = guitars.iterator() ; i.hasNext(); ) {
		Guitar guitar = (Guitar) i.next();
		// ignore serial number since its unique
		// igonre price since that's unique 
		GuitarSpec guitarSpec = guitar.getSpec();
		if (guitarSpec.equals(searchGuitarSpec)) {
			matchingGuitars.add(guitar);
		}
		
		
	}
	return matchingGuitars ;
}