Example
Exporting a macro to allow other modules to use it:
#[macro_export]
// ^~~~~~~~~~~~~~~ Think of it as `pub` for macros.
macro_rules! my_macro { (..) => {..} }
Using macros from other crates or modules:
#[macro_use] extern crate lazy_static;
// ^~~~~~~~~~~~ Must add this in order to use macros from other crates
#[macro_use] mod macros;
// ^~~~~~~~~~~~ The same for child modules.
