Function str_truncated 

pub fn str_truncated(s: &str, max_len: usize) -> DebugValue<TruncatedStr<'_>>

See TruncatedStr. Useful for #[instrument]:

use tuwunel_core::utils::debug::str_truncated;

#[tracing::instrument(fields(foos = str_truncated(foos, 42)))]
fn bar(foos: &str) {}