{"ast_node_type":"other","tokens":[{"end":98,"kind":"keyword","start":0,"text":"self.tcx.fn_arg_idents(fn_def_id).get(expected_idx.as_usize()"}]}
                    self.tcx.fn_arg_idents(fn_def_id).get(expected_idx.as_usize() + self_implicit)
                && let Some(Some(arg)) =
                && arg.name != kw::SelfLower