create method
Implementation
Future<RecipientModel> create(String formId,
{double? longitude, double? latitude}) async {
final Map<String, dynamic> queryParameters = {'form': formId};
if (longitude != null) queryParameters['lng'] = longitude;
if (latitude != null) queryParameters['lat'] = latitude;
final response = await dio.post('/mail', queryParameters: queryParameters);
return RecipientModel.fromJson(response.data);
}