syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:         if !self.serialized_expns.lock().contains(&expn) {
context_before:     pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
context_after:             self.latest_expns.lock().insert(expn);