We call our module world[1], and after studying the services offered by the world server API, we specify it as follows:
| Key | Contents |
| name | The city's name. |
| nat | The city's nationial phone number code. |
| area | The city's area code. |
| utcofs | The city's time zone as an offset to UTC. |
| lat | The latitude of the city's position. |
| long | The longitude of the city's position. |
| country | The name of the country the city is in. |
| capital | The name of the country's capital. |
If the city does not exist, the functions should return null.