| a[0] is a t020 and also not null. | |
| a[1] is a t020 and also a k and also not null. | |
| a[2] is a t020 and also null. | |
| a[3] is a t020 and also null. | |
| Assigning a[0] to u failed. | |
| Assigning a[1] to u worked ok. | |
| Assigning a[2] to u worked ok. | |
| Assigning a[3] to u worked ok. |