syntax_data: {"ast_node_type":"variable","tokens":[{"end":56,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let ret = match v.and_then(|s| s.parse().ok()) {
context_before:     pub(crate) fn parse_threads(slot: &mut usize, v: Option<&str>) -> bool {
context_after:             Some(0) => {