ack is a function.");'
  - text: ''
    testString: 'assert(ack(0, 0) === 1, "ack(0, 0) should return 1.");'
  - text: ''
    testString: 'assert(ack(1, 1) === 3, "ack(1, 1) should return 3.");'
  - text: ''
    testString: 'assert(ack(2, 5) === 13, "ack(2, 5) should return 13.");'
  - text: ''
    testString: 'assert(ack(3, 3) === 61, "ack(3, 3) should return 61.");'
```