syntax_data: {"ast_node_type":"other","tokens":[{"end":1,"kind":"keyword","start":0,"text":"{"}]}
source_snippet: {
context_before:     Copy + Debug + Hash + Eq + Relate<I> + SliceLike<Item = ty::Binder<I, ty::ExistentialPredicate<I>>>
context_after:     fn principal_def_id(self) -> Option<I::DefId>;