Sort the following dataset df by the index column in ascending order and print the result.
+----+--------------------+------------------+---------------------+
| | type_of_dwelling | walls_material | number_of_persons |
|----+--------------------+------------------+---------------------|
| 41 | Private house | wood | 4 |
| 44 | Townhouse | concrete | 8 |
| 42 | Apartment | blocks | 2 |
| 43 | Townhouse | bricks | 3 |
+----+--------------------+------------------+---------------------+