syntax_data: {"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let args = interner.mk_args(&self.args.as_slice()[..args_count]);
context_before:         let args_count = interner.generics_of(def_id).count() - 1;
context_after:         ExistentialTraitRef { def_id, args, _use_existential_trait_ref_new_instead: () }