Example of creating a Gist using Python

init-deep-dive_rust-proc-macro.rs

let mut log_time = false;
    let mut log_ret  = false;

    // Create parser
    let arg_parser = syn::meta::parser(|meta| {
        if meta.path.is_ident("time") {
            log_time = true;
            Ok(())
        } else if meta.path.is_ident("ret") {
            log_ret = true;
            Ok(())
        } else {
            // propagate errors
            Err(meta.error("expected `time` or `ret`"))
        }
    }); 

    let _ = parse_macro_input!(attr with arg_parser);