syntax_data: {"ast_node_type":"other","tokens":[{"end":69,"kind":"keyword","start":0,"text":"//"}]}
source_snippet: // `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
context_before: // It also explains why many functions appear in `HygieneData` and again in
context_after: // `SyntaxContext::outer` do the same thing, but the former is for use within a