Converts a flat-tree to a string. Adapted from mafintosh/print-flat-tree.
sh
$ cargo add print-flat-tree
```txt print-flat-tree Converts a flat-tree to a string
USAGE: print-flat-tree [tree]...
FLAGS: -h, --help Prints help information -V, --version Prints version information
ARGS:
```txt print-flat-tree 0 1 2 3 5 6 7 10 11
0──┐
1──┐
2──┘ │
3──┐
│
│
│
7
8──┐ │
9──┐ │
10──┘ │ │
11──┘
12──┐ │
13──┘
14──┘
````