syntax_data: {"ast_node_type":"variable","tokens":[{"end":43,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let unnormalized_upcast_trait_ref =
context_before:         let mut supertraits = util::supertraits(tcx, ty::Binder::dummy(object_trait_ref));
context_after:             supertraits.nth(index).expect("supertraits iterator no longer has as many elements");