interface MyQueueInterface<E>
   {
      boolean isEmpty(); // returns true is queue is empty
      boolean isFull();  // returns true is queue is full

      void enqueue(E e); // Insert elem e at the back of the queue

      E dequeue();       // Remove the elem at the front
                         // of the queue and return it

      E peek();          // Return the elem at the front
                         // without removing it
   }