syntax_data: {"ast_node_type":"other","tokens":[{"end":98,"kind":"keyword","start":0,"text":"ty::Tuple(tys)"}]}
source_snippet:             ty::Tuple(tys) => std::iter::repeat("_, ").take(tys.len() - 1).chain(["_"]).collect(),
context_before:             ty::Tuple(tys) if tys.is_empty() => "".to_owned(),
context_after:             _ => "_".to_owned(),