syntax_data: {"ast_node_type":"other","tokens":[{"end":29,"kind":"keyword","start":0,"text":"mode:"}]}
source_snippet:         mode: WrapBinderMode,
context_before:         value: &ty::Binder<'tcx, T>,
context_after:     ) -> Result<(T, UnordMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>