{"ast_node_type":"variable","tokens":[{"end":62,"kind":"keyword","start":0,"text":"let"}]}
    let pos = buf.iter().take(10).position(|ch| *ch == b'.')?;
fn ord_list_start(buf: &[u8]) -> Option<(u16, usize)> {
    let n = str::from_utf8(&buf[..pos]).ok()?;