macro_rules! example { ($name:ident) => { ... }; ($name:ident, $width:expr) => { ... }; ($name:ident, $width:expr, $height:expr) => { ... }; }
macro_rules! example { ($name:ident) => { ... }; ($name:ident, $width:expr) => { ... }; ($name:ident, $width:expr, $height:expr) => { ... }; }