+-----+-----+-------+------------+
| a   | b   |     i | x          |
+-----+-----+-------+------------+
| pan | pan |     1 | 0.34679000 |
| eks | wye | 10000 | 0.75868000 |
| wye | hat |    -3 | N/A        |
| hat | zee |     5 |            |
+-----+-----+-------+------------+
