syntax_data: {"ast_node_type":"other","tokens":[{"end":21,"kind":"keyword","start":0,"text":"HygieneData"}]}
source_snippet:         HygieneData {
context_before:         let root_ctxt_data = SyntaxContextData::root();
context_after:             local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),