ArrayString wrapper with truncating Write.
use std::fmt::Write;
use truncating_arraystring::TruncatingArrayString;
fn main() {
let mut buf = TruncatingArrayString::<5>::new();
assert_eq!(write!(buf, "{}", "12"), Ok(()));
assert_eq!(write!(buf, "{}", "3456789"), Err(std::fmt::Error));
assert_eq!(&buf.0[..], "12345");
}