syntax_data: {"ast_node_type":"variable","tokens":[{"end":28,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let index = |ctxt| {
context_before:         // Otherwise small ctxt may enable the partially inline format.
context_after:             with_span_interner(|interner| interner.intern(&SpanData { lo, hi, ctxt, parent }))