{"ast_node_type":"variable","tokens":[{"end":77,"kind":"keyword","start":0,"text":"let"}]}
        let start_entry = self.spans.partition_point(|&(it, _)| it <= start);
        let (start, end) = (range.start(), range.end());
        let end_entry = self.spans[start_entry..].partition_point(|&(it, _)| it <= end); // FIXME: this might be wrong?