Macro flag 

macro_rules! flag {
    () => { ... };
    ($($arg:tt)*) => { ... };
}

Flag

Example

flag!(); //< 2022-12-18T07:02:03(UTC) FLAG crate_name::module_path: [src/main.rs:21]
flag!("i wake up!"); //< 2022-12-18T07:02:03(UTC) FLAG crate_name::module_path: [src/main.rs:21] i wake up!