// An interface for the basic container operations.
// (c) 1996 duane a. bailey

package structure;

public interface Collection extends Container
{
    public boolean contains(Object value);
    // pre: value is non-null
    // post: returns true iff the collection contains the value
    
    public void add(Object value);
    // pre: value is non-null
    // post: the value is added to the collection
    //       the replacement policy is not specified.

    public Object remove(Object value);
    // pre: value is non-null
    // post: removes an object "equal" to value within collection.

    public Iterator elements();
    // post: returns an iterator for traversing collection
}