Macro simd_function 

macro_rules! simd_function {
    (
        $dname:ident,
        $descr:ident: $descr_ty:ident,
        $(#[$($attr:meta)*])*
        $pub:vis fn $name:ident($($arg:ident: $ty:ty),* $(,)?) $(-> $ret:ty )? $body: block
    ) => { ... };
}