Press A to insert code (one number at a time). Enter del to delete the last instruction. Enter nothing to quit inserting code. Press <Space> to execute one step.
Credit to Quintopia (on a different site) At each step, x and then y is popped from the queue. Then, a sequence of x integers is popped from the queue in such a way that popping an empty queue yields 0 (zero). Finally, y copies of this sequence is pushed to the queue.
