package collection;

/**
 * A set of elements different from null.
 *
 * @author Franck van Breugel
 */
public interface Set<T extends Comparable<T>>
{
    /**
     * Tests whether this tree contains the given element.
     * 
     * @param element the element for which to search.
     * @pre. element != null
     * @return true if this tree contains the given element.
     */
    public boolean contains(T element);
    
    /**
     * Attempts to add the given element to this tree.
     * The attempt is successful if this tree does not contain the given element yet.
     * 
     * @param element the element to be inserted.
     * @pre. element != null
     * @return true if the addition is successful, false otherwise.
     */
    public boolean add(T element);
}