syntax_data: {"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":")"}]}
source_snippet:     ) -> Result<(), PrintError> {
context_before:         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
context_after:         self.pretty_print_dyn_existential(predicates)