syntax_data: {"ast_node_type":"variable","tokens":[{"end":99,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
context_before:             data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
context_after:                 debug_expn_data((&id.to_expn_id(), expn_data))