{"ast_node_type":"variable","tokens":[{"end":62,"kind":"keyword","start":0,"text":"let"}]}
        let mut result = Vec::with_capacity(self.num_columns);
        let (row2_start, row2_end) = self.range(row2);
        for (base, (i, j)) in (row1_start..row1_end).zip(row2_start..row2_end).enumerate() {