import objectdraw.*;

/*
 * A list of FilledOvals.  This interface
 * captures what is common about all lists.
 */
public interface BallListInterface {

        // Returns true if the list is empty
        public boolean isEmpty();
        
        // Returns the first ball in the list
        // pre: the list is not an empty list.
        public FilledOval getFirst();
        
        // Returns the rest of the list, after
        // the first ball.
        // pre: the list is not an empty list.
        public BallListInterface getRest();
        
}