syntax_data: {"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let mut locals = IndexVec::<CoroutineSavedLocal, _>::new();
context_before:     // Gather live local types and their indices.
context_after:     let mut tys = IndexVec::<CoroutineSavedLocal, _>::new();