{"ast_node_type":"variable","tokens":[{"end":97,"kind":"keyword","start":0,"text":"let"}]}
    let max_size = var("CHALK_SOLVER_MAX_SIZE").ok().and_then(|s| s.parse().ok()).unwrap_or(150);
        var("CHALK_OVERFLOW_DEPTH").ok().and_then(|s| s.parse().ok()).unwrap_or(500);
    chalk_recursive::RecursiveSolver::new(overflow_depth, max_size, Some(Cache::new()))