syntax_data: {"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"HygieneData::with(|data|"}]}
source_snippet:     HygieneData::with(|data| {
context_before:     let mut to_update = vec![];
context_after:         for (idx, scdata) in data.syntax_context_data.iter().enumerate().rev() {