Code shared from the Rust Playground

playground.rs

    pub fn fmt_value_in(&self, f: &mut fmt::Write, denom: Denomination) -> fmt::Result {
        let sats = self.as_sat().checked_abs().map(|a: i64| a as u64).unwrap_or_else(|| {
            // We could also hard code this into `2147483648`
            u64::max_value() - self.as_sat() as u64 +1
        });
        fmt_satoshi_in(sats, self.is_negative(), f, denom)
    }