Macro filter_emit_seq 

macro_rules! filter_emit_seq {
    ($src_id:expr) => { ... };
    ($event_type:tt, $src_id:expr) => { ... };
    ($supertype:ident, $subtype:ident, $src_id:expr) => { ... };
    ($supertype:ident, $subtype:ident, $scatter:ident, $dir:ident, $src_id:expr) => { ... };
}