{"ast_node_type":"other","tokens":[{"end":99,"kind":"keyword","start":0,"text":".and_then(|uty|"}]}
                .and_then(|uty| self.try_structurally_resolve_type(expr.span, uty).builtin_index())
                .to_option(self)
                .unwrap_or_else(|| self.next_ty_var(expr.span));