Function tree 

pub fn tree(arrow: &Schema) -> SchemaTree

An Arrow schema drawn as a tree: each field with its Arrow type, (required) when it is not nullable, and its metadata; nested fields under their parents.

use arrow_schema::{DataType, Field, Schema, TimeUnit};
use rich::Console;

let schema = Schema::new(vec![
    Field::new("id", DataType::Int64, false),
    Field::new("at", DataType::Timestamp(TimeUnit::Millisecond, Some("UTC".into())), true),
    Field::new("tags", DataType::new_list(DataType::Utf8, true), true),
]);
let console = Console::builder().width(60).color_system(None).build();
assert_eq!(
    console.render_to_string(&rich_data::arrow::tree(&schema)),
    "schema  3 fields\n\
     ├── id (required)  Int64\n\
     ├── at  Timestamp(ms, \"UTC\")\n\
     └── tags  List\n    \
         └── item  Utf8"
);