private static void randomQueueOp( Random rand, Queue<Integer> a, int range ) {
        int op = rand.nextInt( 6 );
        
        switch( op ) {
        case 0: 
        case 1:
        case 5:
        {
            Integer val = rand.nextInt( range );
            a.offer( val );
            break;
        }
        
        case 2: 
        {
            a.poll();
            break;
        }
        
        case 3:
        {
            if( a.size() > 0 ) {
                a.remove();
            }
            break;
        }
        case 4:
            a.peek();
            break;
        }
    }