{"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"impl<S:"}]}
    impl<S: Copy + fmt::Debug> TokenStream<S> {
    /// change these errors into `LexError`s later.
        pub(crate) fn from_str(src: &str, call_site: S) -> Result<TokenStream<S>, String> {