syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"ty::Tuple(tys)"}]}
source_snippet:         ty::Tuple(tys) => Some(SimplifiedType::Tuple(tys.len())),
context_before:         ty::Never => Some(SimplifiedType::Never),
context_after:         ty::FnPtr(sig_tys, _hdr) => {