macro_rules! define_callbacks {
(
$($(#[$attr:meta])*
[$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => { ... };
}
macro_rules! define_callbacks {
(
$($(#[$attr:meta])*
[$($modifiers:tt)*] fn $name:ident($($K:tt)*) -> $V:ty,)*) => { ... };
}