{"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"fmt.debug_struct(\"Arena\").field(\"len\","}]}
        fmt.debug_struct("Arena").field("len", &self.len()).field("data", &self.data).finish()
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
    }