Update IDeque.java

src/edu/caltech/cs2/interfaces/IDeque.java

@@ -23,7 +23,7 @@ public interface IDeque<E> extends ICollection<E> {
    * @param e Element to add
    */
   default public void add(E e){
-    this.addFront(e);
+    this.addBack(e);
   }
 
   /**