{"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"s"}]}
        s if sym::len == *s => Op::Len { depth: parse_depth(&mut args_iter)? },
        s if sym::index == *s => Op::Index { depth: parse_depth(&mut args_iter)? },
        s if sym::count == *s => {