code: public Helix getByLargestContacts() {
  		double contacts = 0;
  		Helix largest = null;
  		for (Helix helix: helices) {
  			if (helix.getContacts() > contacts) {
  				contacts = helix.getContacts();
  				largest = helix;
  			}
  		}
  		return largest;
  	}
docs: /*
  Returns Helix with largest number of intermolecular contacts
  between repeat units