syntax_data: {"ast_node_type":"other","tokens":[{"end":53,"kind":"keyword","start":0,"text":"impl_trait_header:"}]}
source_snippet:         impl_trait_header: ty::ImplTraitHeader<'tcx>,
context_before:         impl_def_id: DefId,
context_after:         obligation: &PolyTraitObligation<'tcx>,