{"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
        let prev_hash_spans = self.hashing_controls.hash_spans;
    pub fn while_hashing_spans<F: FnOnce(&mut Self)>(&mut self, hash_spans: bool, f: F) {
        self.hashing_controls.hash_spans = hash_spans;