{"ast_node_type":"function","tokens":[{"end":66,"kind":"keyword","start":0,"text":"fn"}]}
    fn name_and_extension(&self) -> Option<(&str, Option<&str>)> {
    /// return `Some(("bar.baz", Some("rs"))`.
        let file_path = if self.0.ends_with('/') { &self.0[..&self.0.len() - 1] } else { &self.0 };