macro_rules! dummy_args {
(
$arg:ident $(,$tail:ident)* $(,)?
) => { ... };
(
unsafe $arg:ident $(,$tail:ident)* $(,)?
) => { ... };
(
$($unsafe:ident)?
[$($t:tt)*]
$arg:ident $($tail:ident)*
) => { ... };
(
$($unsafe:ident)?
[$($t:tt)*]
) => { ... };
}