use newtype pattern for TreeIndex
#444
| Job | Run time |
|---|---|
| 2m 56s | |
| 3m 34s | |
| 2m 29s | |
| 2m 59s | |
| 2m 30s | |
| 5m 14s | |
| 9s | |
| 2m 31s | |
| 4m 29s | |
| 25s | |
| 22s | |
| 3m 16s | |
| 3m 13s | |
| 2m 53s | |
| 10m 12s | |
| 3m 20s | |
| 32m 22s | |
| 3m 12s | |
| 27m 28s | |
| 3m 2s | |
| 3m 0s | |
| 2m 58s | |
| 2m 58s | |
| 5m 17s | |
| 4m 4s | |
| 5m 51s | |
| 5m 22s | |
| 7s | |
| 2h 26m 13s |