syntax_data: {"ast_node_type":"other","tokens":[{"end":96,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:     if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
context_before:     // Fast path if the expansion has already been decoded.
context_after:         return expn_id;