I have this list of WorldTime with keys, How do I group these list by the location key.
Below is the code i have written.

```
List<WorldTime> locations = [
    WorldTime(url: 'Europe/London', location: 'London', flag: 'London.png'),
    WorldTime(url: 'Africa/Abidjan',location:'Abidjan'),
    WorldTime(url: 'Africa/Accra', location: 'Accra', flag: 'ghana.png'),
    WorldTime(url: 'Africa/Algeria', location: 'Algiers', flag: 'Algeria.png'),
    WorldTime(url: 'Africa/Guinea ', location: 'Bassau', flag: 'Guinea'),
    WorldTime(url: 'Africa/Cairo', location: 'Cairo', flag: 'Egypt.png'),
    WorldTime(url: 'Africa/Casablanca', location: 'Casablanca', flag: 'Casablanca.png'),
    WorldTime(url: 'Africa/Ceuta ', location: 'Ceuta', flag: 'Ceuta.png'),
    WorldTime(url: 'Africa/El_Aaiun', location: 'El_Aaiun', flag: 'El_Aaiun'),
    WorldTime(url: 'Africa/Johannesburg', location: 'Johannesburg', flag: 'Johannesburg.png'),
    WorldTime(url: 'Africa/Juba', location: 'Juba', flag: 'Juba.png'),
    WorldTime(url: 'Africa/Khartoum', location: 'Khartoum', flag: 'Khartoum.png'),
    WorldTime(url: 'Africa/Lagos', location: 'Lagos', flag: 'Lagos.png'),
    WorldTime(url: 'Africa/Maputo', location: 'Maputo', flag: 'Maputo.png'),
    WorldTime(url: 'Africa/Monrovia', location: 'Monrovia', flag: 'Monrovia.png'),
    WorldTime(url: 'Africa/Nairobi', location: 'Nairobi', flag: 'Nairobi.png'),
    WorldTime(url: 'Africa/Ndjamena', location: 'Ndjamena', flag: 'Ndjamena.png'),
```![End Result](https://i.stack.imgur.com/DVPHK.png)

```