Function optional
pub fn optional<S: Serializer>(span: &Option<Span>, se: S) -> Result<S::Ok, S::Error>Serialize an optional Span in the friendly duration
format using compact designators.
optionalpub fn optional<S: Serializer>(span: &Option<Span>, se: S) -> Result<S::Ok, S::Error>Serialize an optional Span in the friendly duration
format using compact designators.