/**
 * Generic doubly-linked list node. It serves as the basic building block for 
 * storing data in doubly linked chains of nodes.
 * 
 * <b>Do not modify this file in any way!</b>
 */
class DblListnode<E> {
    private DblListnode<E> prev;   // connection to previous node
    private E data;                // data to be stored 
    private DblListnode<E> next;   // connnection to next node

    /**
     * Constructs a new list nodes with no links to neighboring nodes.
     * @param data the data to be stored in this node
     */
    DblListnode(E data) {
        this(null, data, null);
    }
    
    /**
     * Constructs a new list node with links to neighboring nodes.
     * @param prev the node before this one
     * @param data the data to be stored in this node
     * @param next the node after this one
     */
    DblListnode(DblListnode<E> prev, E data, DblListnode<E> next) {
        this.prev = prev;
        this.data = data;
        this.next = next;
    }

    /**
     * Returns the current data.
     * @return the current data
     */
    E getData() {
        return data;
    }

    /**
     * Returns the current next node.
     * @return the current next node
     */
    DblListnode<E> getNext() {
        return next;
    }

    /**
     * Returns the current previous node.
     * @return the current previous node
     */
    DblListnode<E> getPrev() {
        return prev;
    }

    /**
     * Sets the data to the given new value.
     * @param data the new data
     */
    void setData(E data) {
        this.data = data;
    }

    /**
     * Sets the next node to the given new value.
     * @param next the new next node
     */
    void setNext(DblListnode<E> next) {
        this.next = next;
    }

    /**
     * Sets the previous node to the given new value.
     * @param prev the new previous node
     */
    void setPrev(DblListnode<E> prev) {
        this.prev = prev;
    }
}