Macro otel_span 

macro_rules! otel_span {
    ($Name:expr, $Start:expr, $Attrs:expr) => { ... };
    ($Name:expr, $Start:expr) => { ... };
}

Convenience macro: emit an OTLP span for an IPC handler. Usage: otel_span!("file:readFile", StartNano, &[("path", &SomePath)]);