Macro efo 

macro_rules! efo {
    (
        $($args:tt)*
    ) => { ... };
}

eprintln! in a function with offset.

To signify printing within a function. Use to eprintln! in a function.

use si_trace_print::{efn, efx};
use si_trace_print::efo;
fn func1() {
    efo!("hello");
}
fn main() {
    efn!();
    func1();
    efx!();
}

prints

→main:
     func1: hello
←main:

Uses so().