Macro def_remote_sink

macro_rules! def_remote_sink {
    () => { ... };
    ({ $variant_name:ident, $sink_type_name:ident, $sink_name:expr }) => { ... };
    ({ $variant_name:ident, $sink_type_name:ident, $sink_name:expr, |$desc:ident| $body:expr }) => { ... };
    ({ $($first:tt)+ } $({$($rest:tt)+})*) => { ... };
    ($($invalid:tt)*) => { ... };
}