syntax_data: {"ast_node_type":"other","tokens":[{"end":10,"kind":"keyword","start":0,"text":"$("}]}
source_snippet:         $(
context_before:     ($($t:ty),+ $(,)?) => {
context_after:             impl<I: Interner, E: rustc_serialize::Encoder> rustc_serialize::Encodable<E> for ty::Binder<I, $t>