Macro command 

macro_rules! command {
    ($commandName: ident {
        $($arg: ident : $value: expr),* $(,)?
    }) => { ... };
}

A macro for quickly instantiating a float-valued command

For instance:

use g_code::command;
assert_eq!(
    command!(RapidPositioning { X: 0., Y: 1. })
        .iter()
        .fold(String::default(), |s, f| s + &f.to_string()),
    "G0X0Y1"
);