import fi.uef.cs.tra.BTree;
import fi.uef.cs.tra.BTreeNode;
import java.util.Set;

public interface TRAII_25_X1 {

    /**
     * Nodes with two children.
     * Returns a set all the nodes of binary tree T that have at two children.
     * @param T input binary tree
     * @param <E> element type
     * @return set of nodes with two children
     */
    public <E> Set<BTreeNode<E>> twoChildNodes(BTree<E> T);

}