syntax_data: {"ast_node_type":"variable","tokens":[{"end":90,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let trait_ref = ty::TraitRef::relate(relation, trait_ref_a, trait_ref_b)?;
context_before:             (ty::ImplSubject::Trait(trait_ref_a), ty::ImplSubject::Trait(trait_ref_b)) => {
context_after:                 Ok(ty::ImplSubject::Trait(trait_ref))